656542109 has 2 divisors, whose sum is σ = 656542110. Its totient is φ = 656542108.

The previous prime is 656542099. The next prime is 656542151. The reversal of 656542109 is 901245656.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 656486884 + 55225 = 25622^2 + 235^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-656542109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (656542009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328271054 + 328271055.

It is an arithmetic number, because the mean of its divisors is an integer number (328271055).

Almost surely, 2^656542109 is an apocalyptic number.

It is an amenable number.

656542109 is a deficient number, since it is larger than the sum of its proper divisors (1).

656542109 is an equidigital number, since it uses as much as digits as its factorization.

656542109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64800, while the sum is 38.

The square root of 656542109 is about 25623.0776644805. The cubic root of 656542109 is about 869.1355790692.

The spelling of 656542109 in words is "six hundred fifty-six million, five hundred forty-two thousand, one hundred nine".