2531681 has 4 divisors (see below), whose sum is σ = 2536212. Its totient is φ = 2527152.

The previous prime is 2531663. The next prime is 2531687. The reversal of 2531681 is 1861352.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 616225 + 1915456 = 785^2 + 1384^2 .

It is a cyclic number.

It is not a de Polignac number, because 2531681 - 2¹⁸ = 2269537 is a prime.

It is a super-2 number, since 2×2531681² = 12818817371522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2531681.

It is not an unprimeable number, because it can be changed into a prime (2531687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1286 + ... + 2591.

It is an arithmetic number, because the mean of its divisors is an integer number (634053).

2^2531681 is an apocalyptic number.

It is an amenable number.

2531681 is a deficient number, since it is larger than the sum of its proper divisors (4531).

2531681 is an equidigital number, since it uses as much as digits as its factorization.

2531681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4530.

The product of its digits is 1440, while the sum is 26.

The square root of 2531681 is about 1591.1257021367. The cubic root of 2531681 is about 136.2917791244.

The spelling of 2531681 in words is "two million, five hundred thirty-one thousand, six hundred eighty-one".