31678981 has 4 divisors (see below), whose sum is σ = 33056352. Its totient is φ = 30301612.

The previous prime is 31678963. The next prime is 31679029. The reversal of 31678981 is 18987613.

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 31678981 - 2⁷ = 31678853 is a prime.

It is a super-2 number, since 2×31678981² = 2007115674396722, 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 (31678951) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 688651 + ... + 688696.

It is an arithmetic number, because the mean of its divisors is an integer number (8264088).

Almost surely, 2^31678981 is an apocalyptic number.

It is an amenable number.

31678981 is a deficient number, since it is larger than the sum of its proper divisors (1377371).

31678981 is a wasteful number, since it uses less digits than its factorization.

31678981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1377370.

The product of its digits is 72576, while the sum is 43.

The square root of 31678981 is about 5628.4083895894. The cubic root of 31678981 is about 316.4150031271.

It can be divided in two parts, 316 and 78981, that added together give a palindrome (79297).

The spelling of 31678981 in words is "thirty-one million, six hundred seventy-eight thousand, nine hundred eighty-one".