721665093 has 4 divisors (see below), whose sum is σ = 962220128. Its totient is φ = 481110060.

The previous prime is 721665083. The next prime is 721665097. The reversal of 721665093 is 390566127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 721665093 - 2²¹ = 719567941 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 (721665097) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120277513 + ... + 120277518.

It is an arithmetic number, because the mean of its divisors is an integer number (240555032).

Almost surely, 2^721665093 is an apocalyptic number.

It is an amenable number.

721665093 is a deficient number, since it is larger than the sum of its proper divisors (240555035).

721665093 is a wasteful number, since it uses less digits than its factorization.

721665093 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240555034.

The product of its (nonzero) digits is 68040, while the sum is 39.

The square root of 721665093 is about 26863.8249882626. The cubic root of 721665093 is about 896.9713392010.

The spelling of 721665093 in words is "seven hundred twenty-one million, six hundred sixty-five thousand, ninety-three".