51785681 has 16 divisors (see below), whose sum is σ = 55055616. Its totient is φ = 48646656.

The previous prime is 51785663. The next prime is 51785687. The reversal of 51785681 is 18658715.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51785681 is a prime.

It is a super-2 number, since 2×51785681² = 5363513513267522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51785687) 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, 168530 + ... + 168836.

It is an arithmetic number, because the mean of its divisors is an integer number (3440976).

Almost surely, 2^51785681 is an apocalyptic number.

It is an amenable number.

51785681 is a deficient number, since it is larger than the sum of its proper divisors (3269935).

51785681 is a wasteful number, since it uses less digits than its factorization.

51785681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 488.

The product of its digits is 67200, while the sum is 41.

The square root of 51785681 is about 7196.2268585697. The cubic root of 51785681 is about 372.7376223597.

The spelling of 51785681 in words is "fifty-one million, seven hundred eighty-five thousand, six hundred eighty-one".