679721 has 4 divisors (see below), whose sum is σ = 776832. Its totient is φ = 582612.

The previous prime is 679709. The next prime is 679733. The reversal of 679721 is 127976.

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 an interprime number because it is at equal distance from previous prime (679709) and next prime (679733).

It is a cyclic number.

It is not a de Polignac number, because 679721 - 2¹⁸ = 417577 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 679721.

It is not an unprimeable number, because it can be changed into a prime (679741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48545 + ... + 48558.

It is an arithmetic number, because the mean of its divisors is an integer number (194208).

2⁶⁷⁹⁷²¹ is an apocalyptic number.

It is an amenable number.

679721 is a deficient number, since it is larger than the sum of its proper divisors (97111).

679721 is an equidigital number, since it uses as much as digits as its factorization.

679721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97110.

The product of its digits is 5292, while the sum is 32.

The square root of 679721 is about 824.4519391693. The cubic root of 679721 is about 87.9245651756.

The spelling of 679721 in words is "six hundred seventy-nine thousand, seven hundred twenty-one".