20905666 has 32 divisors (see below), whose sum is σ = 34276608. Its totient is φ = 9535680.

The previous prime is 20905663. The next prime is 20905679. The reversal of 20905666 is 66650902.

It is not an unprimeable number, because it can be changed into a prime (20905663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 120756 + ... + 120928.

It is an arithmetic number, because the mean of its divisors is an integer number (1071144).

Almost surely, 2^20905666 is an apocalyptic number.

20905666 is a deficient number, since it is larger than the sum of its proper divisors (13370942).

20905666 is a wasteful number, since it uses less digits than its factorization.

20905666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 306.

The product of its (nonzero) digits is 19440, while the sum is 34.

The square root of 20905666 is about 4572.2714267637. The cubic root of 20905666 is about 275.4786858389.

The spelling of 20905666 in words is "twenty million, nine hundred five thousand, six hundred sixty-six".