51991725820 has 12 divisors (see below), whose sum is σ = 109182624264. Its totient is φ = 20796690320.

The previous prime is 51991725817. The next prime is 51991725833. The reversal of 51991725820 is 2852719915.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1299793126 + ... + 1299793165.

It is an arithmetic number, because the mean of its divisors is an integer number (9098552022).

Almost surely, 2^51991725820 is an apocalyptic number.

It is an amenable number.

51991725820 is an abundant number, since it is smaller than the sum of its proper divisors (57190898444).

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

51991725820 is a wasteful number, since it uses less digits than its factorization.

51991725820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2599586300 (or 2599586298 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 49.

The spelling of 51991725820 in words is "fifty-one billion, nine hundred ninety-one million, seven hundred twenty-five thousand, eight hundred twenty".