51821680 has 20 divisors (see below), whose sum is σ = 120485592. Its totient is φ = 20728640.

The previous prime is 51821659. The next prime is 51821689. The reversal of 51821680 is 8612815.

51821680 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51821689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 323806 + ... + 323965.

Almost surely, 2^51821680 is an apocalyptic number.

It is an amenable number.

51821680 is an abundant number, since it is smaller than the sum of its proper divisors (68663912).

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

51821680 is a wasteful number, since it uses less digits than its factorization.

51821680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 647784 (or 647778 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 51821680 is about 7198.7276653587. The cubic root of 51821680 is about 372.8239723144.

The spelling of 51821680 in words is "fifty-one million, eight hundred twenty-one thousand, six hundred eighty".