31920613 has 4 divisors (see below), whose sum is σ = 31977088. Its totient is φ = 31864140.

The previous prime is 31920571. The next prime is 31920631. The reversal of 31920613 is 31602913.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 31602913 = 167 ⋅189239.

It is a cyclic number.

It is not a de Polignac number, because 31920613 - 2²¹ = 29823461 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 (31920653) 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, 27381 + ... + 28522.

It is an arithmetic number, because the mean of its divisors is an integer number (7994272).

Almost surely, 2^31920613 is an apocalyptic number.

It is an amenable number.

31920613 is a deficient number, since it is larger than the sum of its proper divisors (56475).

31920613 is an equidigital number, since it uses as much as digits as its factorization.

31920613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56474.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 31920613 is about 5649.8330063817. The cubic root of 31920613 is about 317.2174533888.

The spelling of 31920613 in words is "thirty-one million, nine hundred twenty thousand, six hundred thirteen".