66866409 has 12 divisors (see below), whose sum is σ = 96918276. Its totient is φ = 44423712.

The previous prime is 66866399. The next prime is 66866413. The reversal of 66866409 is 90466866.

It can be written as a sum of positive squares in 2 ways, for example, as 45522009 + 21344400 = 6747^2 + 4620^2 .

It is not a de Polignac number, because 66866409 - 2²⁵ = 33311977 is a prime.

It is a super-2 number, since 2×66866409² = 8942233305110562, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66866509) 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, 10042 + ... + 15315.

It is an arithmetic number, because the mean of its divisors is an integer number (8076523).

Almost surely, 2^66866409 is an apocalyptic number.

It is an amenable number.

66866409 is a deficient number, since it is larger than the sum of its proper divisors (30051867).

66866409 is a wasteful number, since it uses less digits than its factorization.

66866409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25656 (or 25653 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The square root of 66866409 is about 8177.1883309607. The cubic root of 66866409 is about 405.8846870135.

The spelling of 66866409 in words is "sixty-six million, eight hundred sixty-six thousand, four hundred nine".