666156609 has 32 divisors (see below), whose sum is σ = 1008128640. Its totient is φ = 434647296.

The previous prime is 666156499. The next prime is 666156637. The reversal of 666156609 is 906651666.

It is not a de Polignac number, because 666156609 - 2⁷ = 666156481 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666156109) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 268794 + ... + 271260.

It is an arithmetic number, because the mean of its divisors is an integer number (31504020).

Almost surely, 2^666156609 is an apocalyptic number.

It is an amenable number.

666156609 is a deficient number, since it is larger than the sum of its proper divisors (341972031).

666156609 is a wasteful number, since it uses less digits than its factorization.

666156609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2686 (or 2680 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The square root of 666156609 is about 25810.0098605173. The cubic root of 666156609 is about 873.3576196880.

The spelling of 666156609 in words is "six hundred sixty-six million, one hundred fifty-six thousand, six hundred nine".