721969636 has 12 divisors (see below), whose sum is σ = 1269114112. Its totient is φ = 359365608.

The previous prime is 721969631. The next prime is 721969639. The reversal of 721969636 is 636969127.

It is a self number, because there is not a number n which added to its sum of digits gives 721969636.

It is not an unprimeable number, because it can be changed into a prime (721969631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 403800 + ... + 405583.

Almost surely, 2^721969636 is an apocalyptic number.

It is an amenable number.

721969636 is a deficient number, since it is larger than the sum of its proper divisors (547144476).

721969636 is a wasteful number, since it uses less digits than its factorization.

721969636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 809610 (or 809608 counting only the distinct ones).

The product of its digits is 734832, while the sum is 49.

The square root of 721969636 is about 26869.4926636139. The cubic root of 721969636 is about 897.0974955621.

The spelling of 721969636 in words is "seven hundred twenty-one million, nine hundred sixty-nine thousand, six hundred thirty-six".