31890613 has 4 divisors (see below), whose sum is σ = 31971340. Its totient is φ = 31809888.

The previous prime is 31890611. The next prime is 31890629. The reversal of 31890613 is 31609813.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24039409 + 7851204 = 4903^2 + 2802^2 .

It is a cyclic number.

It is not a de Polignac number, because 31890613 - 2¹ = 31890611 is a prime.

It is a super-2 number, since 2×31890613² = 2034022395031538, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31890611) 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, 39768 + ... + 40561.

It is an arithmetic number, because the mean of its divisors is an integer number (7992835).

Almost surely, 2^31890613 is an apocalyptic number.

It is an amenable number.

31890613 is a deficient number, since it is larger than the sum of its proper divisors (80727).

31890613 is an equidigital number, since it uses as much as digits as its factorization.

31890613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80726.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 31890613 is about 5647.1774365607. The cubic root of 31890613 is about 317.1180452470.

The spelling of 31890613 in words is "thirty-one million, eight hundred ninety thousand, six hundred thirteen".