721881864 has 144 divisors (see below), whose sum is σ = 2230890480. Its totient is φ = 209119680.

The previous prime is 721881827. The next prime is 721881871. The reversal of 721881864 is 468188127.

It is a super-2 number, since 2×721881864² = 1042226851144228992, which contains 22 as substring.

Its product of digits (172032) is a multiple of the sum of its prime factors (1792).

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 418107 + ... + 419829.

It is an arithmetic number, because the mean of its divisors is an integer number (15492295).

Almost surely, 2^721881864 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 721881864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1115445240).

721881864 is an abundant number, since it is smaller than the sum of its proper divisors (1509008616).

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

721881864 is a wasteful number, since it uses less digits than its factorization.

721881864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1792 (or 1762 counting only the distinct ones).

The product of its digits is 172032, while the sum is 45.

The square root of 721881864 is about 26867.8593118246. The cubic root of 721881864 is about 897.0611398168.

The spelling of 721881864 in words is "seven hundred twenty-one million, eight hundred eighty-one thousand, eight hundred sixty-four".