656020991 has 8 divisors (see below), whose sum is σ = 663534480. Its totient is φ = 648523008.

The previous prime is 656020921. The next prime is 656020993. The reversal of 656020991 is 199020656.

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

It is a cyclic number.

It is not a de Polignac number, because 656020991 - 2¹⁴ = 656004607 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 (656020993) 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, 95525 + ... + 102161.

It is an arithmetic number, because the mean of its divisors is an integer number (82941810).

Almost surely, 2^656020991 is an apocalyptic number.

656020991 is a deficient number, since it is larger than the sum of its proper divisors (7513489).

656020991 is a wasteful number, since it uses less digits than its factorization.

656020991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7753.

The product of its (nonzero) digits is 29160, while the sum is 38.

The square root of 656020991 is about 25612.9067268828. The cubic root of 656020991 is about 868.9055648405.

The spelling of 656020991 in words is "six hundred fifty-six million, twenty thousand, nine hundred ninety-one".