20866931 has 4 divisors (see below), whose sum is σ = 21082152. Its totient is φ = 20651712.

The previous prime is 20866913. The next prime is 20866933. The reversal of 20866931 is 13966802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20866931 - 2¹⁴ = 20850547 is a prime.

It is a super-2 number, since 2×20866931² = 870857618717522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20866891 and 20866900.

It is not an unprimeable number, because it can be changed into a prime (20866933) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107465 + ... + 107658.

It is an arithmetic number, because the mean of its divisors is an integer number (5270538).

Almost surely, 2^20866931 is an apocalyptic number.

20866931 is a deficient number, since it is larger than the sum of its proper divisors (215221).

20866931 is an equidigital number, since it uses as much as digits as its factorization.

20866931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215220.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 20866931 is about 4568.0336032039. The cubic root of 20866931 is about 275.3084406996.

The spelling of 20866931 in words is "twenty million, eight hundred sixty-six thousand, nine hundred thirty-one".