51505661631 has 4 divisors (see below), whose sum is σ = 68674215512. Its totient is φ = 34337107752.

The previous prime is 51505661629. The next prime is 51505661659. The reversal of 51505661631 is 13616650515.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 51505661631 - 2¹ = 51505661629 is a prime.

It is a super-2 number, since 2×51505661631² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51505661631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51505661621) 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, 8584276936 + ... + 8584276941.

It is an arithmetic number, because the mean of its divisors is an integer number (17168553878).

Almost surely, 2^51505661631 is an apocalyptic number.

51505661631 is a deficient number, since it is larger than the sum of its proper divisors (17168553881).

51505661631 is a wasteful number, since it uses less digits than its factorization.

51505661631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17168553880.

The product of its (nonzero) digits is 81000, while the sum is 39.

The spelling of 51505661631 in words is "fifty-one billion, five hundred five million, six hundred sixty-one thousand, six hundred thirty-one".