15721660416 has 512 divisors, whose sum is σ = 54759997440. Its totient is φ = 3892838400.

The previous prime is 15721660391. The next prime is 15721660421. The reversal of 15721660416 is 61406612751.

It is a tau number, because it is divible by the number of its divisors (512).

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, 234651615 + ... + 234651681.

It is an arithmetic number, because the mean of its divisors is an integer number (106953120).

Almost surely, 2^15721660416 is an apocalyptic number.

15721660416 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15721660416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27379998720).

15721660416 is an abundant number, since it is smaller than the sum of its proper divisors (39038337024).

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

15721660416 is an equidigital number, since it uses as much as digits as its factorization.

15721660416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149 (or 121 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 39.

The spelling of 15721660416 in words is "fifteen billion, seven hundred twenty-one million, six hundred sixty thousand, four hundred sixteen".