666809450 has 24 divisors (see below), whose sum is σ = 1241006508. Its totient is φ = 266564480.

The previous prime is 666809443. The next prime is 666809453. The reversal of 666809450 is 54908666.

It can be written as a sum of positive squares in 6 ways, for example, as 808201 + 666001249 = 899^2 + 25807^2 .

It is a hoax number, since the sum of its digits (44) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (666809453) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 116864 + ... + 122436.

Almost surely, 2^666809450 is an apocalyptic number.

666809450 is a deficient number, since it is larger than the sum of its proper divisors (574197058).

666809450 is a wasteful number, since it uses less digits than its factorization.

666809450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7978 (or 7973 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 44.

The square root of 666809450 is about 25822.6538140448. The cubic root of 666809450 is about 873.6428266497.

The spelling of 666809450 in words is "six hundred sixty-six million, eight hundred nine thousand, four hundred fifty".