51081991356 has 24 divisors (see below), whose sum is σ = 130026887424. Its totient is φ = 15479391280.

The previous prime is 51081991339. The next prime is 51081991361. The reversal of 51081991356 is 65319918015.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 193492260 + ... + 193492523.

It is an arithmetic number, because the mean of its divisors is an integer number (5417786976).

Almost surely, 2^51081991356 is an apocalyptic number.

It is an amenable number.

51081991356 is an abundant number, since it is smaller than the sum of its proper divisors (78944896068).

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

51081991356 is a wasteful number, since it uses less digits than its factorization.

51081991356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386984801 (or 386984799 counting only the distinct ones).

The product of its (nonzero) digits is 291600, while the sum is 48.

The spelling of 51081991356 in words is "fifty-one billion, eighty-one million, nine hundred ninety-one thousand, three hundred fifty-six".