51696655921 has 4 divisors (see below), whose sum is σ = 51710734372. Its totient is φ = 51682577472.

The previous prime is 51696655909. The next prime is 51696655931. The reversal of 51696655921 is 12955669615.

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 24700522896 + 26996133025 = 157164^2 + 164305^2 .

It is a cyclic number.

It is not a de Polignac number, because 51696655921 - 2⁵ = 51696655889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51696655931) 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, 7033716 + ... + 7041061.

It is an arithmetic number, because the mean of its divisors is an integer number (12927683593).

Almost surely, 2^51696655921 is an apocalyptic number.

It is an amenable number.

51696655921 is a deficient number, since it is larger than the sum of its proper divisors (14078451).

51696655921 is a wasteful number, since it uses less digits than its factorization.

51696655921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14078450.

The product of its digits is 4374000, while the sum is 55.

The spelling of 51696655921 in words is "fifty-one billion, six hundred ninety-six million, six hundred fifty-five thousand, nine hundred twenty-one".