20917866 has 16 divisors (see below), whose sum is σ = 42809184. Its totient is φ = 6810384.

The previous prime is 20917861. The next prime is 20917873. The reversal of 20917866 is 66871902.

It is not an unprimeable number, because it can be changed into a prime (20917861) 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, 40281 + ... + 40796.

It is an arithmetic number, because the mean of its divisors is an integer number (2675574).

Almost surely, 2^20917866 is an apocalyptic number.

20917866 is an abundant number, since it is smaller than the sum of its proper divisors (21891318).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20917866 is a wasteful number, since it uses less digits than its factorization.

20917866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81125.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 20917866 is about 4573.6053612003. The cubic root of 20917866 is about 275.5322628040.

The spelling of 20917866 in words is "twenty million, nine hundred seventeen thousand, eight hundred sixty-six".