538657681 has 3 divisors (see below), whose sum is σ = 538680891. Its totient is φ = 538634472.

The previous prime is 538657661. The next prime is 538657739. The reversal of 538657681 is 186756835.

The square root of 538657681 is 23209.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 186756835 = 5 ⋅37351367.

It can be written as a sum of positive squares in only one way, i.e., 400360081 + 138297600 = 20009^2 + 11760^2 .

It is not a de Polignac number, because 538657681 - 2⁵ = 538657649 is a prime.

It is a super-2 number, since 2×538657681² = 580304194600595522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (538657621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 11605 + ... + 34813.

It is an arithmetic number, because the mean of its divisors is an integer number (179560297).

Almost surely, 2^538657681 is an apocalyptic number.

538657681 is the 23209-th square number.

538657681 is the 11605-th centered octagonal number.

It is an amenable number.

538657681 is a deficient number, since it is larger than the sum of its proper divisors (23210).

538657681 is an frugal number, since it uses more digits than its factorization.

538657681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46418 (or 23209 counting only the distinct ones).

The product of its digits is 1209600, while the sum is 49.

The cubic root of 538657681 is about 813.6499817217.

Multiplying 538657681 by its sum of digits (49), we get a square (26394226369 = 162463²).

The spelling of 538657681 in words is "five hundred thirty-eight million, six hundred fifty-seven thousand, six hundred eighty-one".