51217561720 has 32 divisors (see below), whose sum is σ = 124104093120. Its totient is φ = 18911099520.

The previous prime is 51217561711. The next prime is 51217561729. The reversal of 51217561720 is 2716571215.

It is an interprime number because it is at equal distance from previous prime (51217561711) and next prime (51217561729).

It is a self number, because there is not a number n which added to its sum of digits gives 51217561720.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51217561729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49247136 + ... + 49248175.

It is an arithmetic number, because the mean of its divisors is an integer number (3878252910).

Almost surely, 2^51217561720 is an apocalyptic number.

It is an amenable number.

51217561720 is an abundant number, since it is smaller than the sum of its proper divisors (72886531400).

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

51217561720 is a wasteful number, since it uses less digits than its factorization.

51217561720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98495335 (or 98495331 counting only the distinct ones).

The product of its (nonzero) digits is 29400, while the sum is 37.

The spelling of 51217561720 in words is "fifty-one billion, two hundred seventeen million, five hundred sixty-one thousand, seven hundred twenty".