31713991 has 4 divisors (see below), whose sum is σ = 31746312. Its totient is φ = 31681672.

The previous prime is 31713989. The next prime is 31714013. The reversal of 31713991 is 19931713.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19931713 = 47 ⋅424079.

It is a cyclic number.

It is not a de Polignac number, because 31713991 - 2¹ = 31713989 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 (31713971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14641 + ... + 16666.

It is an arithmetic number, because the mean of its divisors is an integer number (7936578).

Almost surely, 2^31713991 is an apocalyptic number.

31713991 is a deficient number, since it is larger than the sum of its proper divisors (32321).

31713991 is a wasteful number, since it uses less digits than its factorization.

31713991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32320.

The product of its digits is 5103, while the sum is 34.

The square root of 31713991 is about 5631.5176462478. The cubic root of 31713991 is about 316.5315221415.

The spelling of 31713991 in words is "thirty-one million, seven hundred thirteen thousand, nine hundred ninety-one".