721868643 has 12 divisors (see below), whose sum is σ = 1042959840. Its totient is φ = 481125456.

The previous prime is 721868633. The next prime is 721868657. The reversal of 721868643 is 346868127.

It is not a de Polignac number, because 721868643 - 2⁴ = 721868627 is a prime.

It is a super-2 number, since 2×721868643² = 1042188675493322898, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (721868633) 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, 42405 + ... + 56937.

It is an arithmetic number, because the mean of its divisors is an integer number (86913320).

Almost surely, 2^721868643 is an apocalyptic number.

721868643 is a deficient number, since it is larger than the sum of its proper divisors (321091197).

721868643 is a wasteful number, since it uses less digits than its factorization.

721868643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20058 (or 20055 counting only the distinct ones).

The product of its digits is 387072, while the sum is 45.

The square root of 721868643 is about 26867.6132732329. The cubic root of 721868643 is about 897.0556633354.

The spelling of 721868643 in words is "seven hundred twenty-one million, eight hundred sixty-eight thousand, six hundred forty-three".