51645680 has 20 divisors (see below), whose sum is σ = 120076392. Its totient is φ = 20658240.

The previous prime is 51645661. The next prime is 51645701. The reversal of 51645680 is 8654615.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 51645680.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 322706 + ... + 322865.

Almost surely, 2^51645680 is an apocalyptic number.

It is an amenable number.

51645680 is an abundant number, since it is smaller than the sum of its proper divisors (68430712).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51645680 is a wasteful number, since it uses less digits than its factorization.

51645680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 645584 (or 645578 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 35.

The square root of 51645680 is about 7186.4928859632. The cubic root of 51645680 is about 372.4014243011.

It can be divided in two parts, 51645 and 680, that added together give a palindrome (52325).

The spelling of 51645680 in words is "fifty-one million, six hundred forty-five thousand, six hundred eighty".