666091945 has 32 divisors (see below), whose sum is σ = 848395296. Its totient is φ = 501350400.

The previous prime is 666091939. The next prime is 666091961. The reversal of 666091945 is 549190666.

It can be written as a sum of positive squares in 16 ways, for example, as 37687321 + 628404624 = 6139^2 + 25068^2 .

It is not a de Polignac number, because 666091945 - 2⁷ = 666091817 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 666091895 and 666091904.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1038825 + ... + 1039465.

It is an arithmetic number, because the mean of its divisors is an integer number (26512353).

Almost surely, 2^666091945 is an apocalyptic number.

It is an amenable number.

666091945 is a deficient number, since it is larger than the sum of its proper divisors (182303351).

666091945 is a wasteful number, since it uses less digits than its factorization.

666091945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 861.

The product of its (nonzero) digits is 349920, while the sum is 46.

The square root of 666091945 is about 25808.7571378399. The cubic root of 666091945 is about 873.3293597544.

The spelling of 666091945 in words is "six hundred sixty-six million, ninety-one thousand, nine hundred forty-five".