721511616 has 56 divisors (see below), whose sum is σ = 2181717760. Its totient is φ = 206145792.

The previous prime is 721511611. The next prime is 721511627. The reversal of 721511616 is 616115127.

It is a tau number, because it is divible by the number of its divisors (56).

It is not an unprimeable number, because it can be changed into a prime (721511611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 267076 + ... + 269763.

Almost surely, 2^721511616 is an apocalyptic number.

It is an amenable number.

721511616 is an abundant number, since it is smaller than the sum of its proper divisors (1460206144).

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

721511616 is a wasteful number, since it uses less digits than its factorization.

721511616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536861 (or 536851 counting only the distinct ones).

The product of its digits is 2520, while the sum is 30.

The square root of 721511616 is about 26860.9682625180. The cubic root of 721511616 is about 896.9077481938.

The spelling of 721511616 in words is "seven hundred twenty-one million, five hundred eleven thousand, six hundred sixteen".