51213131 has 4 divisors (see below), whose sum is σ = 51616512. Its totient is φ = 50809752.

The previous prime is 51213119. The next prime is 51213137. The reversal of 51213131 is 13131215.

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

It is a cyclic number.

It is not a de Polignac number, because 51213131 - 2⁶ = 51213067 is a prime.

It is a super-2 number, since 2×51213131² = 5245569573646322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51213137) 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, 201500 + ... + 201753.

It is an arithmetic number, because the mean of its divisors is an integer number (12904128).

Almost surely, 2^51213131 is an apocalyptic number.

51213131 is a deficient number, since it is larger than the sum of its proper divisors (403381).

51213131 is a wasteful number, since it uses less digits than its factorization.

51213131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403380.

The product of its digits is 90, while the sum is 17.

The square root of 51213131 is about 7156.3350256958. The cubic root of 51213131 is about 371.3588480918.

Adding to 51213131 its reverse (13131215), we get a palindrome (64344346).

The spelling of 51213131 in words is "fifty-one million, two hundred thirteen thousand, one hundred thirty-one".