721970815689 has 12 divisors (see below), whose sum is σ = 1043695282500. Its totient is φ = 480922239264.

The previous prime is 721970815673. The next prime is 721970815711. The reversal of 721970815689 is 986518079127.

It can be written as a sum of positive squares in 2 ways, for example, as 607983551289 + 113987264400 = 779733^2 + 337620^2 .

It is not a de Polignac number, because 721970815689 - 2⁴ = 721970815673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (721970815669) 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, 32624814 + ... + 32646935.

It is an arithmetic number, because the mean of its divisors is an integer number (86974606875).

Almost surely, 2^721970815689 is an apocalyptic number.

It is an amenable number.

721970815689 is a deficient number, since it is larger than the sum of its proper divisors (321724466811).

721970815689 is a wasteful number, since it uses less digits than its factorization.

721970815689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65272984 (or 65272981 counting only the distinct ones).

The product of its (nonzero) digits is 15240960, while the sum is 63.

The spelling of 721970815689 in words is "seven hundred twenty-one billion, nine hundred seventy million, eight hundred fifteen thousand, six hundred eighty-nine".