51621165 has 32 divisors (see below), whose sum is σ = 93340800. Its totient is φ = 27060480.

The previous prime is 51621161. The next prime is 51621209. The reversal of 51621165 is 56112615.

It is a happy number.

It is not a de Polignac number, because 51621165 - 2² = 51621161 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51621161) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4725 + ... + 11205.

It is an arithmetic number, because the mean of its divisors is an integer number (2916900).

Almost surely, 2^51621165 is an apocalyptic number.

It is an amenable number.

51621165 is a deficient number, since it is larger than the sum of its proper divisors (41719635).

51621165 is a wasteful number, since it uses less digits than its factorization.

51621165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6554 (or 6548 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 51621165 is about 7184.7870532118. The cubic root of 51621165 is about 372.3424915513.

The spelling of 51621165 in words is "fifty-one million, six hundred twenty-one thousand, one hundred sixty-five".