402631981 has 4 divisors (see below), whose sum is σ = 402730272. Its totient is φ = 402533692.

The previous prime is 402631979. The next prime is 402631991. The reversal of 402631981 is 189136204.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 402631981 - 2¹ = 402631979 is a prime.

It is a super-2 number, since 2×402631981² = 324225024247968722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402631991) 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, 42721 + ... + 51286.

It is an arithmetic number, because the mean of its divisors is an integer number (100682568).

Almost surely, 2^402631981 is an apocalyptic number.

It is an amenable number.

402631981 is a deficient number, since it is larger than the sum of its proper divisors (98291).

402631981 is an equidigital number, since it uses as much as digits as its factorization.

402631981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98290.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 402631981 is about 20065.6916402102. The cubic root of 402631981 is about 738.4188182688.

The spelling of 402631981 in words is "four hundred two million, six hundred thirty-one thousand, nine hundred eighty-one".