31981568 has 40 divisors (see below), whose sum is σ = 65011650. Its totient is φ = 15728640.

The previous prime is 31981567. The next prime is 31981583. The reversal of 31981568 is 86518913.

It can be written as a sum of positive squares in only one way, i.e., 31719424 + 262144 = 5632^2 + 512^2 .

It is not an unprimeable number, because it can be changed into a prime (31981567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 524258 + ... + 524318.

Almost surely, 2^31981568 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31981568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32505825).

31981568 is an abundant number, since it is smaller than the sum of its proper divisors (33030082).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31981568 is an frugal number, since it uses more digits than its factorization.

31981568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99 (or 63 counting only the distinct ones).

The product of its digits is 51840, while the sum is 41.

The square root of 31981568 is about 5655.2248407999. The cubic root of 31981568 is about 317.4192424859.

The spelling of 31981568 in words is "thirty-one million, nine hundred eighty-one thousand, five hundred sixty-eight".