51721725408 has 96 divisors (see below), whose sum is σ = 137305808640. Its totient is φ = 17045852160.

The previous prime is 51721725397. The next prime is 51721725457. The reversal of 51721725408 is 80452712715.

It is a tau number, because it is divible by the number of its divisors (96).

It is a self number, because there is not a number n which added to its sum of digits gives 51721725408.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12280423 + ... + 12284633.

It is an arithmetic number, because the mean of its divisors is an integer number (1430268840).

Almost surely, 2^51721725408 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 51721725408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68652904320).

51721725408 is an abundant number, since it is smaller than the sum of its proper divisors (85584083232).

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

51721725408 is a wasteful number, since it uses less digits than its factorization.

51721725408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5640 (or 5632 counting only the distinct ones).

The product of its (nonzero) digits is 156800, while the sum is 42.

The spelling of 51721725408 in words is "fifty-one billion, seven hundred twenty-one million, seven hundred twenty-five thousand, four hundred eight".