656486991 has 32 divisors (see below), whose sum is σ = 996477120. Its totient is φ = 426995712.

The previous prime is 656486989. The next prime is 656487001. The reversal of 656486991 is 199684656.

It is a happy number.

It is not a de Polignac number, because 656486991 - 2¹ = 656486989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656486911) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 274995 + ... + 277371.

It is an arithmetic number, because the mean of its divisors is an integer number (31139910).

Almost surely, 2^656486991 is an apocalyptic number.

656486991 is a deficient number, since it is larger than the sum of its proper divisors (339990129).

656486991 is a wasteful number, since it uses less digits than its factorization.

656486991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2632 (or 2626 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 54.

The square root of 656486991 is about 25622.0020880492. The cubic root of 656486991 is about 869.1112565087. Note that the first 3 decimals are identical.

The spelling of 656486991 in words is "six hundred fifty-six million, four hundred eighty-six thousand, nine hundred ninety-one".