679781721 has 32 divisors (see below), whose sum is σ = 982056960. Its totient is φ = 416972864.

The previous prime is 679781701. The next prime is 679781731. The reversal of 679781721 is 127187976.

It is a cyclic number.

It is not a de Polignac number, because 679781721 - 2⁵ = 679781689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (679781701) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 765940 + ... + 766826.

It is an arithmetic number, because the mean of its divisors is an integer number (30689280).

Almost surely, 2^679781721 is an apocalyptic number.

It is an amenable number.

679781721 is a deficient number, since it is larger than the sum of its proper divisors (302275239).

679781721 is a wasteful number, since it uses less digits than its factorization.

679781721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1325.

The product of its digits is 296352, while the sum is 48.

The square root of 679781721 is about 26072.6239761172. The cubic root of 679781721 is about 879.2718326381.

The spelling of 679781721 in words is "six hundred seventy-nine million, seven hundred eighty-one thousand, seven hundred twenty-one".