656139091 has 2 divisors, whose sum is σ = 656139092. Its totient is φ = 656139090.

The previous prime is 656139079. The next prime is 656139109. The reversal of 656139091 is 190931656.

Together with next prime (656139109) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 656139091 - 2¹³ = 656130899 is a prime.

It is not a weakly prime, because it can be changed into another prime (656137091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328069545 + 328069546.

It is an arithmetic number, because the mean of its divisors is an integer number (328069546).

Almost surely, 2^656139091 is an apocalyptic number.

656139091 is a deficient number, since it is larger than the sum of its proper divisors (1).

656139091 is an equidigital number, since it uses as much as digits as its factorization.

656139091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43740, while the sum is 40.

The square root of 656139091 is about 25615.2121014057. The cubic root of 656139091 is about 868.9577032077.

The spelling of 656139091 in words is "six hundred fifty-six million, one hundred thirty-nine thousand, ninety-one".