20866881 has 16 divisors (see below), whose sum is σ = 32033664. Its totient is φ = 11835264.

The previous prime is 20866877. The next prime is 20866897. The reversal of 20866881 is 18866802.

It is not a de Polignac number, because 20866881 - 2² = 20866877 is a prime.

It is a super-2 number, since 2×20866881² = 870853445336322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20866801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 750 + ... + 6503.

It is an arithmetic number, because the mean of its divisors is an integer number (2002104).

Almost surely, 2^20866881 is an apocalyptic number.

20866881 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20866881 is a deficient number, since it is larger than the sum of its proper divisors (11166783).

20866881 is a wasteful number, since it uses less digits than its factorization.

20866881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7400.

The product of its (nonzero) digits is 36864, while the sum is 39.

The square root of 20866881 is about 4568.0281303862. The cubic root of 20866881 is about 275.3082208073.

The spelling of 20866881 in words is "twenty million, eight hundred sixty-six thousand, eight hundred eighty-one".