661456979 has 4 divisors (see below), whose sum is σ = 668006160. Its totient is φ = 654907800.

The previous prime is 661456933. The next prime is 661457053. The reversal of 661456979 is 979654166.

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 661456979 - 2²⁸ = 393021523 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661456979.

It is not an unprimeable number, because it can be changed into a prime (661456909) 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, 3274439 + ... + 3274640.

It is an arithmetic number, because the mean of its divisors is an integer number (167001540).

Almost surely, 2^661456979 is an apocalyptic number.

661456979 is a deficient number, since it is larger than the sum of its proper divisors (6549181).

661456979 is a wasteful number, since it uses less digits than its factorization.

661456979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6549180.

The product of its digits is 2449440, while the sum is 53.

The square root of 661456979 is about 25718.8059404009. The cubic root of 661456979 is about 871.2989707535.

The spelling of 661456979 in words is "six hundred sixty-one million, four hundred fifty-six thousand, nine hundred seventy-nine".