721624661 has 8 divisors (see below), whose sum is σ = 747832800. Its totient is φ = 695504880.

The previous prime is 721624649. The next prime is 721624669. The reversal of 721624661 is 166426127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721624661 - 2⁶ = 721624597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721624669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5231 + ... + 38348.

It is an arithmetic number, because the mean of its divisors is an integer number (93479100).

Almost surely, 2^721624661 is an apocalyptic number.

It is an amenable number.

721624661 is a deficient number, since it is larger than the sum of its proper divisors (26208139).

721624661 is a wasteful number, since it uses less digits than its factorization.

721624661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44179.

The product of its digits is 24192, while the sum is 35.

The square root of 721624661 is about 26863.0724415507. The cubic root of 721624661 is about 896.9545876529.

The spelling of 721624661 in words is "seven hundred twenty-one million, six hundred twenty-four thousand, six hundred sixty-one".