51721808 has 40 divisors (see below), whose sum is σ = 103445760. Its totient is φ = 25038720.

The previous prime is 51721807. The next prime is 51721841. The reversal of 51721808 is 80812715.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51721801) 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 7 ways as a sum of consecutive naturals, for example, 81653 + ... + 82283.

It is an arithmetic number, because the mean of its divisors is an integer number (2586144).

Almost surely, 2^51721808 is an apocalyptic number.

It is an amenable number.

51721808 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

51721808 is a wasteful number, since it uses less digits than its factorization.

51721808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 795 (or 789 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 51721808 is about 7191.7875385748. The cubic root of 51721808 is about 372.5843131521.

The spelling of 51721808 in words is "fifty-one million, seven hundred twenty-one thousand, eight hundred eight".