51665720 has 32 divisors (see below), whose sum is σ = 123087600. Its totient is φ = 19450368.

The previous prime is 51665711. The next prime is 51665723. The reversal of 51665720 is 2756615.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51665723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37310 + ... + 38669.

Almost surely, 2^51665720 is an apocalyptic number.

It is an amenable number.

51665720 is an abundant number, since it is smaller than the sum of its proper divisors (71421880).

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

51665720 is a wasteful number, since it uses less digits than its factorization.

51665720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76007 (or 76003 counting only the distinct ones).

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 51665720 is about 7187.8870330578. The cubic root of 51665720 is about 372.4495855379.

The spelling of 51665720 in words is "fifty-one million, six hundred sixty-five thousand, seven hundred twenty".