51111515661 has 4 divisors (see below), whose sum is σ = 68148687552. Its totient is φ = 34074343772.

The previous prime is 51111515659. The next prime is 51111515671. The reversal of 51111515661 is 16651511115.

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 not a de Polignac number, because 51111515661 - 2¹ = 51111515659 is a prime.

It is a super-2 number, since 2×51111515661² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51111515671) 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, 8518585941 + ... + 8518585946.

It is an arithmetic number, because the mean of its divisors is an integer number (17037171888).

Almost surely, 2^51111515661 is an apocalyptic number.

It is an amenable number.

51111515661 is a deficient number, since it is larger than the sum of its proper divisors (17037171891).

51111515661 is a wasteful number, since it uses less digits than its factorization.

51111515661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17037171890.

The product of its digits is 4500, while the sum is 33.

The spelling of 51111515661 in words is "fifty-one billion, one hundred eleven million, five hundred fifteen thousand, six hundred sixty-one".