721305679 has 4 divisors (see below), whose sum is σ = 722004976. Its totient is φ = 720606384.

The previous prime is 721305649. The next prime is 721305703. The reversal of 721305679 is 976503127.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 721305679 - 2²⁵ = 687751247 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 (721305649) 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, 348099 + ... + 350164.

It is an arithmetic number, because the mean of its divisors is an integer number (180501244).

Almost surely, 2^721305679 is an apocalyptic number.

721305679 is a deficient number, since it is larger than the sum of its proper divisors (699297).

721305679 is a wasteful number, since it uses less digits than its factorization.

721305679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 699296.

The product of its (nonzero) digits is 79380, while the sum is 40.

The square root of 721305679 is about 26857.1346014425. The cubic root of 721305679 is about 896.8224069635.

The spelling of 721305679 in words is "seven hundred twenty-one million, three hundred five thousand, six hundred seventy-nine".