656498406591 has 12 divisors (see below), whose sum is σ = 948361990680. Its totient is φ = 437625674640.

The previous prime is 656498406569. The next prime is 656498406643. The reversal of 656498406591 is 195604894656.

656498406591 is a `hidden beast` number, since 6 + 56 + 4 + 98 + 406 + 5 + 91 = 666.

It is not a de Polignac number, because 656498406591 - 2¹¹ = 656498404543 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656498406691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3223180 + ... + 3420801.

It is an arithmetic number, because the mean of its divisors is an integer number (79030165890).

Almost surely, 2^656498406591 is an apocalyptic number.

656498406591 is a deficient number, since it is larger than the sum of its proper divisors (291863584089).

656498406591 is a wasteful number, since it uses less digits than its factorization.

656498406591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6654966 (or 6654963 counting only the distinct ones).

The product of its (nonzero) digits is 55987200, while the sum is 63.

The spelling of 656498406591 in words is "six hundred fifty-six billion, four hundred ninety-eight million, four hundred six thousand, five hundred ninety-one".