31972991 has 8 divisors (see below), whose sum is σ = 33972480. Its totient is φ = 30005208.

The previous prime is 31972987. The next prime is 31973009. The reversal of 31972991 is 19927913.

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 31972991 - 2² = 31972987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31972901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5831 + ... + 9896.

It is an arithmetic number, because the mean of its divisors is an integer number (4246560).

Almost surely, 2^31972991 is an apocalyptic number.

31972991 is a deficient number, since it is larger than the sum of its proper divisors (1999489).

31972991 is a wasteful number, since it uses less digits than its factorization.

31972991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15853.

The product of its digits is 30618, while the sum is 41.

The square root of 31972991 is about 5654.4664646631. The cubic root of 31972991 is about 317.3908641790.

The spelling of 31972991 in words is "thirty-one million, nine hundred seventy-two thousand, nine hundred ninety-one".