51813457920 has 1120 divisors, whose sum is σ = 223798595328. Its totient is φ = 11211374592.

The previous prime is 51813457831. The next prime is 51813457967. The reversal of 51813457920 is 2975431815.

51813457920 is a `hidden beast` number, since 51 + 8 + 1 + 3 + 4 + 579 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (1120).

It is a super-2 number, since 2×51813457920² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 534159312 + ... + 534159408.

Almost surely, 2^51813457920 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 51813457920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (111899297664).

51813457920 is an abundant number, since it is smaller than the sum of its proper divisors (171985137408).

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

51813457920 is an equidigital number, since it uses as much as digits as its factorization.

51813457920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The spelling of 51813457920 in words is "fifty-one billion, eight hundred thirteen million, four hundred fifty-seven thousand, nine hundred twenty".