21211139 has 2 divisors, whose sum is σ = 21211140. Its totient is φ = 21211138.

The previous prime is 21211109. The next prime is 21211181. The reversal of 21211139 is 93111212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211139 is a prime.

It is a Chen prime.

It is equal to p_1342442 and since 21211139 and 1342442 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21211139.

It is not a weakly prime, because it can be changed into another prime (21211109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605569 + 10605570.

It is an arithmetic number, because the mean of its divisors is an integer number (10605570).

Almost surely, 2^21211139 is an apocalyptic number.

21211139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211139 is an equidigital number, since it uses as much as digits as its factorization.

21211139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108, while the sum is 20.

The square root of 21211139 is about 4605.5552325425. Note that the first 3 decimals coincide. The cubic root of 21211139 is about 276.8139653693.

The spelling of 21211139 in words is "twenty-one million, two hundred eleven thousand, one hundred thirty-nine".