51621057216 has 448 divisors, whose sum is σ = 164679782400. Its totient is φ = 15814656000.

The previous prime is 51621057199. The next prime is 51621057217. The reversal of 51621057216 is 61275012615.

51621057216 is a `hidden beast` number, since 5 + 1 + 62 + 10 + 572 + 16 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (51621057217) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 128730616 + ... + 128731016.

It is an arithmetic number, because the mean of its divisors is an integer number (367588800).

Almost surely, 2^51621057216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51621057216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82339891200).

51621057216 is an abundant number, since it is smaller than the sum of its proper divisors (113058725184).

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

51621057216 is a wasteful number, since it uses less digits than its factorization.

51621057216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 565 (or 549 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 36.

The spelling of 51621057216 in words is "fifty-one billion, six hundred twenty-one million, fifty-seven thousand, two hundred sixteen".