51207051661 has 4 divisors (see below), whose sum is σ = 51216702300. Its totient is φ = 51197401024.

The previous prime is 51207051647. The next prime is 51207051667. The reversal of 51207051661 is 16615070215.

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 17690596036 + 33516455625 = 133006^2 + 183075^2 .

It is a cyclic number.

It is not a de Polignac number, because 51207051661 - 2²⁵ = 51173497229 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 (51207051667) 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, 4817356 + ... + 4827973.

It is an arithmetic number, because the mean of its divisors is an integer number (12804175575).

Almost surely, 2^51207051661 is an apocalyptic number.

It is an amenable number.

51207051661 is a deficient number, since it is larger than the sum of its proper divisors (9650639).

51207051661 is an equidigital number, since it uses as much as digits as its factorization.

51207051661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9650638.

The product of its (nonzero) digits is 12600, while the sum is 34.

The spelling of 51207051661 in words is "fifty-one billion, two hundred seven million, fifty-one thousand, six hundred sixty-one".