51781774821 has 16 divisors (see below), whose sum is σ = 78924355200. Its totient is φ = 29582538048.

The previous prime is 51781774819. The next prime is 51781774829. The reversal of 51781774821 is 12847718715.

It is not a de Polignac number, because 51781774821 - 2¹ = 51781774819 is a prime.

It is a super-2 number, since 2×51781774821² (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 (51781774829) 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, 202726 + ... + 380343.

It is an arithmetic number, because the mean of its divisors is an integer number (4932772200).

Almost surely, 2^51781774821 is an apocalyptic number.

It is an amenable number.

51781774821 is a deficient number, since it is larger than the sum of its proper divisors (27142580379).

51781774821 is a wasteful number, since it uses less digits than its factorization.

51781774821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587308.

The product of its digits is 878080, while the sum is 51.

The spelling of 51781774821 in words is "fifty-one billion, seven hundred eighty-one million, seven hundred seventy-four thousand, eight hundred twenty-one".