51991036020 has 576 divisors, whose sum is σ = 201478717440. Its totient is φ = 10540108800.

The previous prime is 51991035977. The next prime is 51991036043. The reversal of 51991036020 is 2063019915.

51991036020 is a `hidden beast` number, since 519 + 91 + 0 + 36 + 0 + 20 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 112778590 + ... + 112779050.

It is an arithmetic number, because the mean of its divisors is an integer number (349789440).

Almost surely, 2^51991036020 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 51991036020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100739358720).

51991036020 is an abundant number, since it is smaller than the sum of its proper divisors (149487681420).

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

51991036020 is a wasteful number, since it uses less digits than its factorization.

51991036020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 676 (or 671 counting only the distinct ones).

The product of its (nonzero) digits is 14580, while the sum is 36.

The spelling of 51991036020 in words is "fifty-one billion, nine hundred ninety-one million, thirty-six thousand, twenty".