20666409 has 8 divisors (see below), whose sum is σ = 27605280. Its totient is φ = 13752576.

The previous prime is 20666389. The next prime is 20666413. The reversal of 20666409 is 90466602.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20666409 - 2⁵ = 20666377 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20666409.

It is not an unprimeable number, because it can be changed into a prime (20666209) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4239 + ... + 7700.

It is an arithmetic number, because the mean of its divisors is an integer number (3450660).

Almost surely, 2^20666409 is an apocalyptic number.

It is an amenable number.

20666409 is a deficient number, since it is larger than the sum of its proper divisors (6938871).

20666409 is a wasteful number, since it uses less digits than its factorization.

20666409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12519.

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 20666409 is about 4546.0322260186. The cubic root of 20666409 is about 274.4237365320.

The spelling of 20666409 in words is "twenty million, six hundred sixty-six thousand, four hundred nine".