721644443 has 16 divisors (see below), whose sum is σ = 804249600. Its totient is φ = 643019040.

The previous prime is 721644409. The next prime is 721644479. The reversal of 721644443 is 344446127.

It is a cyclic number.

It is not a de Polignac number, because 721644443 - 2⁶ = 721644379 is a prime.

It is a super-2 number, since 2×721644443² = 1041541404225560498, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721644743) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 174878 + ... + 178956.

It is an arithmetic number, because the mean of its divisors is an integer number (50265600).

Almost surely, 2^721644443 is an apocalyptic number.

721644443 is a deficient number, since it is larger than the sum of its proper divisors (82605157).

721644443 is a wasteful number, since it uses less digits than its factorization.

721644443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4562.

The product of its digits is 64512, while the sum is 35.

The square root of 721644443 is about 26863.4406396500. The cubic root of 721644443 is about 896.9627836928.

The spelling of 721644443 in words is "seven hundred twenty-one million, six hundred forty-four thousand, four hundred forty-three".