20866409 has 8 divisors (see below), whose sum is σ = 21490368. Its totient is φ = 20245680.

The previous prime is 20866387. The next prime is 20866411. The reversal of 20866409 is 90466802.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20866409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20860409) 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, 19724 + ... + 20754.

It is an arithmetic number, because the mean of its divisors is an integer number (2686296).

Almost surely, 2^20866409 is an apocalyptic number.

It is an amenable number.

20866409 is a deficient number, since it is larger than the sum of its proper divisors (623959).

20866409 is a wasteful number, since it uses less digits than its factorization.

20866409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1615.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 20866409 is about 4567.9764666644. The cubic root of 20866409 is about 275.3061450066.

The spelling of 20866409 in words is "twenty million, eight hundred sixty-six thousand, four hundred nine".