51531613 has 4 divisors (see below), whose sum is σ = 58893280. Its totient is φ = 44169948.

The previous prime is 51531593. The next prime is 51531617. The reversal of 51531613 is 31613515.

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: 31613515 = 5 ⋅6322703.

It is a cyclic number.

It is not a de Polignac number, because 51531613 - 2²⁵ = 17977181 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 (51531617) 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, 3680823 + ... + 3680836.

It is an arithmetic number, because the mean of its divisors is an integer number (14723320).

Almost surely, 2^51531613 is an apocalyptic number.

It is an amenable number.

51531613 is a deficient number, since it is larger than the sum of its proper divisors (7361667).

51531613 is an equidigital number, since it uses as much as digits as its factorization.

51531613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7361666.

The product of its digits is 1350, while the sum is 25.

The square root of 51531613 is about 7178.5522913746. The cubic root of 51531613 is about 372.1270546270.

The spelling of 51531613 in words is "fifty-one million, five hundred thirty-one thousand, six hundred thirteen".