20249281 has 4 divisors (see below), whose sum is σ = 21806932. Its totient is φ = 18691632.

The previous prime is 20249267. The next prime is 20249291. The reversal of 20249281 is 18294202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18294202 = 2 ⋅9147101.

It can be written as a sum of positive squares in 2 ways, for example, as 810000 + 19439281 = 900^2 + 4409^2 .

It is a cyclic number.

It is not a de Polignac number, because 20249281 - 2⁷ = 20249153 is a prime.

It is a super-2 number, since 2×20249281² = 820066762033922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20249291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 778806 + ... + 778831.

It is an arithmetic number, because the mean of its divisors is an integer number (5451733).

Almost surely, 2^20249281 is an apocalyptic number.

It is an amenable number.

20249281 is a deficient number, since it is larger than the sum of its proper divisors (1557651).

20249281 is a wasteful number, since it uses less digits than its factorization.

20249281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1557650.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 20249281 is about 4499.9201104020. The cubic root of 20249281 is about 272.5648629367.

It can be divided in two parts, 2024928 and 1, that added together give a square (2024929 = 1423²).

The spelling of 20249281 in words is "twenty million, two hundred forty-nine thousand, two hundred eighty-one".