656991619 has 8 divisors (see below), whose sum is σ = 686403360. Its totient is φ = 627650496.

The previous prime is 656991589. The next prime is 656991623. The reversal of 656991619 is 916199656.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 656991619 - 2²¹ = 654894467 is a prime.

It is a super-2 number, since 2×656991619² = 863275974872482322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (656991659) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1839 + ... + 36295.

It is an arithmetic number, because the mean of its divisors is an integer number (85800420).

Almost surely, 2^656991619 is an apocalyptic number.

656991619 is a deficient number, since it is larger than the sum of its proper divisors (29411741).

656991619 is a wasteful number, since it uses less digits than its factorization.

656991619 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35309.

The product of its digits is 787320, while the sum is 52.

The square root of 656991619 is about 25631.8477484554. The cubic root of 656991619 is about 869.3338887690. Note that the first 3 decimals are identical.

The spelling of 656991619 in words is "six hundred fifty-six million, nine hundred ninety-one thousand, six hundred nineteen".