51630640 has 20 divisors (see below), whose sum is σ = 120041424. Its totient is φ = 20652224.

The previous prime is 51630613. The next prime is 51630641. The reversal of 51630640 is 4603615.

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

It is not an unprimeable number, because it can be changed into a prime (51630641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 322612 + ... + 322771.

Almost surely, 2^51630640 is an apocalyptic number.

It is an amenable number.

51630640 is an abundant number, since it is smaller than the sum of its proper divisors (68410784).

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

51630640 is a wasteful number, since it uses less digits than its factorization.

51630640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 645396 (or 645390 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 51630640 is about 7185.4464022773. The cubic root of 51630640 is about 372.3652711565.

The spelling of 51630640 in words is "fifty-one million, six hundred thirty thousand, six hundred forty".