51668718381 has 24 divisors (see below), whose sum is σ = 88045827584. Its totient is φ = 28572562080.

The previous prime is 51668718359. The next prime is 51668718383. The reversal of 51668718381 is 18381786615.

51668718381 is a `hidden beast` number, since 516 + 6 + 87 + 18 + 38 + 1 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-51668718381 is a prime.

It is a super-2 number, since 2×51668718381² (a number of 22 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51668718383) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13226086 + ... + 13229991.

Almost surely, 2^51668718381 is an apocalyptic number.

It is an amenable number.

51668718381 is a deficient number, since it is larger than the sum of its proper divisors (36377109203).

51668718381 is a wasteful number, since it uses less digits than its factorization.

51668718381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26456121 (or 26456118 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 54.

The spelling of 51668718381 in words is "fifty-one billion, six hundred sixty-eight million, seven hundred eighteen thousand, three hundred eighty-one".