31981390 has 16 divisors (see below), whose sum is σ = 65790432. Its totient is φ = 10965024.

The previous prime is 31981361. The next prime is 31981399. The reversal of 31981390 is 9318913.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31981399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 228369 + ... + 228508.

It is an arithmetic number, because the mean of its divisors is an integer number (4111902).

Almost surely, 2^31981390 is an apocalyptic number.

31981390 is an abundant number, since it is smaller than the sum of its proper divisors (33809042).

31981390 is a wasteful number, since it uses less digits than its factorization.

31981390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 456891.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 31981390 is about 5655.2091031190. The cubic root of 31981390 is about 317.4186535974.

The spelling of 31981390 in words is "thirty-one million, nine hundred eighty-one thousand, three hundred ninety".