721645056 has 240 divisors, whose sum is σ = 2374669440. Its totient is φ = 208834560.

The previous prime is 721645027. The next prime is 721645069. The reversal of 721645056 is 650546127.

It is a happy number.

721645056 is a `hidden beast` number, since 7 + 2 + 1 + 645 + 0 + 5 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 721645056.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 1165515 + ... + 1166133.

It is an arithmetic number, because the mean of its divisors is an integer number (9894456).

Almost surely, 2^721645056 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 721645056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1187334720).

721645056 is an abundant number, since it is smaller than the sum of its proper divisors (1653024384).

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

721645056 is a wasteful number, since it uses less digits than its factorization.

721645056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677 (or 658 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 36.

The square root of 721645056 is about 26863.4520492062. The cubic root of 721645056 is about 896.9630376674.

The spelling of 721645056 in words is "seven hundred twenty-one million, six hundred forty-five thousand, fifty-six".