51718981 has 16 divisors (see below), whose sum is σ = 56548800. Its totient is φ = 47109888.

The previous prime is 51718957. The next prime is 51718991. The reversal of 51718981 is 18981715.

It is a cyclic number.

It is not a de Polignac number, because 51718981 - 2⁵ = 51718949 is a prime.

It is a super-2 number, since 2×51718981² = 5349705991356722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51718991) 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, 101355 + ... + 101863.

It is an arithmetic number, because the mean of its divisors is an integer number (3534300).

Almost surely, 2^51718981 is an apocalyptic number.

It is an amenable number.

51718981 is a deficient number, since it is larger than the sum of its proper divisors (4829819).

51718981 is a wasteful number, since it uses less digits than its factorization.

51718981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708.

The product of its digits is 20160, while the sum is 40.

The square root of 51718981 is about 7191.5909922631. The cubic root of 51718981 is about 372.5775248160.

The spelling of 51718981 in words is "fifty-one million, seven hundred eighteen thousand, nine hundred eighty-one".