666961659 has 48 divisors (see below), whose sum is σ = 1237297152. Its totient is φ = 336498624.

The previous prime is 666961643. The next prime is 666961721. The reversal of 666961659 is 956169666.

It is a happy number.

It is not a de Polignac number, because 666961659 - 2⁴ = 666961643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666961159) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1134 + ... + 36540.

It is an arithmetic number, because the mean of its divisors is an integer number (25777024).

Almost surely, 2^666961659 is an apocalyptic number.

666961659 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

666961659 is a deficient number, since it is larger than the sum of its proper divisors (570335493).

666961659 is a wasteful number, since it uses less digits than its factorization.

666961659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35456 (or 35453 counting only the distinct ones).

The product of its digits is 3149280, while the sum is 54.

The square root of 666961659 is about 25825.6008448981. The cubic root of 666961659 is about 873.7092955059.

The spelling of 666961659 in words is "six hundred sixty-six million, nine hundred sixty-one thousand, six hundred fifty-nine".