721616436 has 36 divisors (see below), whose sum is σ = 1826278272. Its totient is φ = 240249744.

The previous prime is 721616383. The next prime is 721616437. The reversal of 721616436 is 634616127.

It is a happy number.

721616436 is a `hidden beast` number, since 7 + 2 + 1 + 6 + 1 + 643 + 6 = 666.

721616436 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (36).

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 721616436.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721616437) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19455 + ... + 42681.

It is an arithmetic number, because the mean of its divisors is an integer number (50729952).

Almost surely, 2^721616436 is an apocalyptic number.

It is an amenable number.

721616436 is an abundant number, since it is smaller than the sum of its proper divisors (1104661836).

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

721616436 is a wasteful number, since it uses less digits than its factorization.

721616436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24100 (or 24095 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 721616436 is about 26862.9193499143. The cubic root of 721616436 is about 896.9511798428.

The spelling of 721616436 in words is "seven hundred twenty-one million, six hundred sixteen thousand, four hundred thirty-six".