51443876821 has 4 divisors (see below), whose sum is σ = 51510774700. Its totient is φ = 51376978944.

The previous prime is 51443876773. The next prime is 51443876849. The reversal of 51443876821 is 12867834415.

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 15322973796 + 36120903025 = 123786^2 + 190055^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51443876821 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 (51443876321) 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, 33447786 + ... + 33449323.

It is an arithmetic number, because the mean of its divisors is an integer number (12877693675).

Almost surely, 2^51443876821 is an apocalyptic number.

It is an amenable number.

51443876821 is a deficient number, since it is larger than the sum of its proper divisors (66897879).

51443876821 is an equidigital number, since it uses as much as digits as its factorization.

51443876821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66897878.

The product of its digits is 1290240, while the sum is 49.

The spelling of 51443876821 in words is "fifty-one billion, four hundred forty-three million, eight hundred seventy-six thousand, eight hundred twenty-one".