659557981 has 2 divisors, whose sum is σ = 659557982. Its totient is φ = 659557980.

The previous prime is 659557931. The next prime is 659558033. The reversal of 659557981 is 189755956.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 442260900 + 217297081 = 21030^2 + 14741^2 .

It is a cyclic number.

It is not a de Polignac number, because 659557981 - 2²³ = 651169373 is a prime.

It is a super-2 number, since 2×659557981² = 870033460601592722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (659557901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 329778990 + 329778991.

It is an arithmetic number, because the mean of its divisors is an integer number (329778991).

Almost surely, 2^659557981 is an apocalyptic number.

It is an amenable number.

659557981 is a deficient number, since it is larger than the sum of its proper divisors (1).

659557981 is an equidigital number, since it uses as much as digits as its factorization.

659557981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3402000, while the sum is 55.

The square root of 659557981 is about 25681.8609333514. The cubic root of 659557981 is about 870.4643581756.

The spelling of 659557981 in words is "six hundred fifty-nine million, five hundred fifty-seven thousand, nine hundred eighty-one".