721665983 has 2 divisors, whose sum is σ = 721665984. Its totient is φ = 721665982.

The previous prime is 721665979. The next prime is 721666013. The reversal of 721665983 is 389566127.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 721665983 - 2² = 721665979 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721665953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360832991 + 360832992.

It is an arithmetic number, because the mean of its divisors is an integer number (360832992).

Almost surely, 2^721665983 is an apocalyptic number.

721665983 is a deficient number, since it is larger than the sum of its proper divisors (1).

721665983 is an equidigital number, since it uses as much as digits as its factorization.

721665983 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 47.

The square root of 721665983 is about 26863.8415532850. The cubic root of 721665983 is about 896.9717079335.

The spelling of 721665983 in words is "seven hundred twenty-one million, six hundred sixty-five thousand, nine hundred eighty-three".