51431213021 has 4 divisors (see below), whose sum is σ = 51484400352. Its totient is φ = 51378025692.

The previous prime is 51431212999. The next prime is 51431213023. The reversal of 51431213021 is 12031213415.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51431213021 is a prime.

It is a super-2 number, since 2×51431213021² (a number of 22 digits) 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 (51431213023) 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, 26592215 + ... + 26594148.

It is an arithmetic number, because the mean of its divisors is an integer number (12871100088).

Almost surely, 2^51431213021 is an apocalyptic number.

It is an amenable number.

51431213021 is a deficient number, since it is larger than the sum of its proper divisors (53187331).

51431213021 is an equidigital number, since it uses as much as digits as its factorization.

51431213021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53187330.

The product of its (nonzero) digits is 720, while the sum is 23.

Adding to 51431213021 its reverse (12031213415), we get a palindrome (63462426436).

The spelling of 51431213021 in words is "fifty-one billion, four hundred thirty-one million, two hundred thirteen thousand, twenty-one".