31696721 has 8 divisors (see below), whose sum is σ = 38355840. Its totient is φ = 25570368.

The previous prime is 31696711. The next prime is 31696723. The reversal of 31696721 is 12769613.

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 31696721 - 2⁶ = 31696657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31696723) 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, 133061 + ... + 133298.

It is an arithmetic number, because the mean of its divisors is an integer number (4794480).

Almost surely, 2^31696721 is an apocalyptic number.

It is an amenable number.

31696721 is a deficient number, since it is larger than the sum of its proper divisors (6659119).

31696721 is a wasteful number, since it uses less digits than its factorization.

31696721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266383.

The product of its digits is 13608, while the sum is 35.

The square root of 31696721 is about 5629.9841029971. The cubic root of 31696721 is about 316.4740554757.

The spelling of 31696721 in words is "thirty-one million, six hundred ninety-six thousand, seven hundred twenty-one".