31997281 has 8 divisors (see below), whose sum is σ = 34010280. Its totient is φ = 29998848.

The previous prime is 31997249. The next prime is 31997299. The reversal of 31997281 is 18279913.

It can be written as a sum of positive squares in 4 ways, for example, as 1083681 + 30913600 = 1041^2 + 5560^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31997281 - 2⁵ = 31997249 is a prime.

It is a super-2 number, since 2×31997281² = 2047651982785922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31997201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1075 + ... + 8071.

It is an arithmetic number, because the mean of its divisors is an integer number (4251285).

Almost surely, 2^31997281 is an apocalyptic number.

It is an amenable number.

31997281 is a deficient number, since it is larger than the sum of its proper divisors (2012999).

31997281 is a wasteful number, since it uses less digits than its factorization.

31997281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7283.

The product of its digits is 27216, while the sum is 40.

The square root of 31997281 is about 5656.6139164698. The cubic root of 31997281 is about 317.4712181734.

The spelling of 31997281 in words is "thirty-one million, nine hundred ninety-seven thousand, two hundred eighty-one".