31713721 has 8 divisors (see below), whose sum is σ = 36162504. Its totient is φ = 27552000.

The previous prime is 31713683. The next prime is 31713749. The reversal of 31713721 is 12731713.

It can be written as a sum of positive squares in 4 ways, for example, as 230400 + 31483321 = 480^2 + 5611^2 .

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 31713721 - 2⁷ = 31713593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31713761) 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, 71530 + ... + 71971.

It is an arithmetic number, because the mean of its divisors is an integer number (4520313).

Almost surely, 2^31713721 is an apocalyptic number.

It is an amenable number.

31713721 is a deficient number, since it is larger than the sum of its proper divisors (4448783).

31713721 is a wasteful number, since it uses less digits than its factorization.

31713721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143531.

The product of its digits is 882, while the sum is 25.

The square root of 31713721 is about 5631.4936739732. The cubic root of 31713721 is about 316.5306238654.

The spelling of 31713721 in words is "thirty-one million, seven hundred thirteen thousand, seven hundred twenty-one".