400831981 has 16 divisors (see below), whose sum is σ = 442573056. Its totient is φ = 363000000.

The previous prime is 400831979. The next prime is 400831993. The reversal of 400831981 is 189138004.

It is a happy number.

It is not a de Polignac number, because 400831981 - 2¹ = 400831979 is a prime.

It is a super-2 number, since 2×400831981² = 321332553984768722, 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 (400831931) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 533356 + ... + 534106.

It is an arithmetic number, because the mean of its divisors is an integer number (27660816).

Almost surely, 2^400831981 is an apocalyptic number.

It is an amenable number.

400831981 is a deficient number, since it is larger than the sum of its proper divisors (41741075).

400831981 is an equidigital number, since it uses as much as digits as its factorization.

400831981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1185 (or 1163 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 400831981 is about 20020.7887207273. The cubic root of 400831981 is about 737.3167866637.

Adding to 400831981 its reverse (189138004), we get a palindrome (589969985).

The spelling of 400831981 in words is "four hundred million, eight hundred thirty-one thousand, nine hundred eighty-one".