21866137 has 2 divisors, whose sum is σ = 21866138. Its totient is φ = 21866136.

The previous prime is 21866113. The next prime is 21866189. The reversal of 21866137 is 73166812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20620681 + 1245456 = 4541^2 + 1116^2 .

It is a cyclic number.

It is not a de Polignac number, because 21866137 - 2¹⁵ = 21833369 is a prime.

It is not a weakly prime, because it can be changed into another prime (21866737) 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 as a sum of consecutive naturals, namely, 10933068 + 10933069.

It is an arithmetic number, because the mean of its divisors is an integer number (10933069).

Almost surely, 2^21866137 is an apocalyptic number.

It is an amenable number.

21866137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21866137 is an equidigital number, since it uses as much as digits as its factorization.

21866137 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 34.

The square root of 21866137 is about 4676.1241429201. The cubic root of 21866137 is about 279.6344592176.

The spelling of 21866137 in words is "twenty-one million, eight hundred sixty-six thousand, one hundred thirty-seven".