51515661565 has 16 divisors (see below), whose sum is σ = 62106849792. Its totient is φ = 41020739584.

The previous prime is 51515661559. The next prime is 51515661569. The reversal of 51515661565 is 56516651515.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 51515661565 - 2⁷ = 51515661437 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 (51515661569) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1741932 + ... + 1771258.

It is an arithmetic number, because the mean of its divisors is an integer number (3881678112).

Almost surely, 2^51515661565 is an apocalyptic number.

It is an amenable number.

51515661565 is a deficient number, since it is larger than the sum of its proper divisors (10591188227).

51515661565 is a wasteful number, since it uses less digits than its factorization.

51515661565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30956.

The product of its digits is 675000, while the sum is 46.

The spelling of 51515661565 in words is "fifty-one billion, five hundred fifteen million, six hundred sixty-one thousand, five hundred sixty-five".