31801990 has 16 divisors (see below), whose sum is σ = 62447760. Its totient is φ = 11564320.

The previous prime is 31801969. The next prime is 31802021. The reversal of 31801990 is 9910813.

It is a super-2 number, since 2×31801990² = 2022733135920200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 144445 + ... + 144664.

It is an arithmetic number, because the mean of its divisors is an integer number (3902985).

Almost surely, 2^31801990 is an apocalyptic number.

31801990 is a deficient number, since it is larger than the sum of its proper divisors (30645770).

31801990 is a wasteful number, since it uses less digits than its factorization.

31801990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289127.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 31801990 is about 5639.3253142552. The cubic root of 31801990 is about 316.8240190590.

The spelling of 31801990 in words is "thirty-one million, eight hundred one thousand, nine hundred ninety".