51656421 has 16 divisors (see below), whose sum is σ = 76766400. Its totient is φ = 30705408.

The previous prime is 51656417. The next prime is 51656471. The reversal of 51656421 is 12465615.

51656421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 51656421 - 2² = 51656417 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51656411) 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 15 ways as a sum of consecutive naturals, for example, 25686 + ... + 27623.

It is an arithmetic number, because the mean of its divisors is an integer number (4797900).

Almost surely, 2^51656421 is an apocalyptic number.

51656421 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

51656421 is a deficient number, since it is larger than the sum of its proper divisors (25109979).

51656421 is a wasteful number, since it uses less digits than its factorization.

51656421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53348.

The product of its digits is 7200, while the sum is 30.

The square root of 51656421 is about 7187.2401518246. The cubic root of 51656421 is about 372.4272392155.

The spelling of 51656421 in words is "fifty-one million, six hundred fifty-six thousand, four hundred twenty-one".