658661 has 4 divisors (see below), whose sum is σ = 660300. Its totient is φ = 657024.

The previous prime is 658649. The next prime is 658663. The reversal of 658661 is 166856.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 42436 + 616225 = 206^2 + 785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-658661 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 (658663) 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, 245 + ... + 1173.

It is an arithmetic number, because the mean of its divisors is an integer number (165075).

2⁶⁵⁸⁶⁶¹ is an apocalyptic number.

It is an amenable number.

658661 is a deficient number, since it is larger than the sum of its proper divisors (1639).

658661 is an equidigital number, since it uses as much as digits as its factorization.

658661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1638.

The product of its digits is 8640, while the sum is 32.

The square root of 658661 is about 811.5793245272. The cubic root of 658661 is about 87.0069576503.

The spelling of 658661 in words is "six hundred fifty-eight thousand, six hundred sixty-one".