721721904 has 40 divisors (see below), whose sum is σ = 1883681520. Its totient is φ = 238092288.

The previous prime is 721721863. The next prime is 721721909. The reversal of 721721904 is 409127127.

It is not an unprimeable number, because it can be changed into a prime (721721909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72849 + ... + 82160.

It is an arithmetic number, because the mean of its divisors is an integer number (47092038).

Almost surely, 2^721721904 is an apocalyptic number.

It is an amenable number.

721721904 is an abundant number, since it is smaller than the sum of its proper divisors (1161959616).

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

721721904 is a wasteful number, since it uses less digits than its factorization.

721721904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155117 (or 155111 counting only the distinct ones).

The product of its (nonzero) digits is 7056, while the sum is 33.

The square root of 721721904 is about 26864.8823559680. The cubic root of 721721904 is about 896.9948757427.

The spelling of 721721904 in words is "seven hundred twenty-one million, seven hundred twenty-one thousand, nine hundred four".