655844991 has 4 divisors (see below), whose sum is σ = 874459992. Its totient is φ = 437229992.

The previous prime is 655844971. The next prime is 655844999. The reversal of 655844991 is 199448556.

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 655844991 - 2⁶ = 655844927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655844999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109307496 + ... + 109307501.

It is an arithmetic number, because the mean of its divisors is an integer number (218614998).

Almost surely, 2^655844991 is an apocalyptic number.

655844991 is a deficient number, since it is larger than the sum of its proper divisors (218615001).

655844991 is a wasteful number, since it uses less digits than its factorization.

655844991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218615000.

The product of its digits is 1555200, while the sum is 51.

The square root of 655844991 is about 25609.4707286191. The cubic root of 655844991 is about 868.8278533752.

The spelling of 655844991 in words is "six hundred fifty-five million, eight hundred forty-four thousand, nine hundred ninety-one".