661579 has 4 divisors (see below), whose sum is σ = 663984. Its totient is φ = 659176.

The previous prime is 661553. The next prime is 661603. The reversal of 661579 is 975166.

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 661579 - 2⁵ = 661547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661679) 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, 727 + ... + 1360.

It is an arithmetic number, because the mean of its divisors is an integer number (165996).

2⁶⁶¹⁵⁷⁹ is an apocalyptic number.

661579 is a deficient number, since it is larger than the sum of its proper divisors (2405).

661579 is a wasteful number, since it uses less digits than its factorization.

661579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2404.

The product of its digits is 11340, while the sum is 34.

The square root of 661579 is about 813.3750672353. The cubic root of 661579 is about 87.1352544525.

It can be divided in two parts, 66157 and 9, that added together give a palindrome (66166).

The spelling of 661579 in words is "six hundred sixty-one thousand, five hundred seventy-nine".