51021978840 has 128 divisors (see below), whose sum is σ = 194369472000. Its totient is φ = 11662164864.

The previous prime is 51021978817. The next prime is 51021978857. The reversal of 51021978840 is 4887912015.

51021978840 is a `hidden beast` number, since 510 + 2 + 1 + 97 + 8 + 8 + 40 = 666.

51021978840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 31 ways as a sum of consecutive naturals, for example, 3366910 + ... + 3382029.

It is an arithmetic number, because the mean of its divisors is an integer number (1518511500).

Almost surely, 2^51021978840 is an apocalyptic number.

It is an amenable number.

51021978840 is an abundant number, since it is smaller than the sum of its proper divisors (143347493160).

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

51021978840 is a wasteful number, since it uses less digits than its factorization.

51021978840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6748966 (or 6748956 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 45.

The spelling of 51021978840 in words is "fifty-one billion, twenty-one million, nine hundred seventy-eight thousand, eight hundred forty".