21844139 has 2 divisors, whose sum is σ = 21844140. Its totient is φ = 21844138.

The previous prime is 21844117. The next prime is 21844159. The reversal of 21844139 is 93144812.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21844139 - 2²⁰ = 20795563 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21844159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10922069 + 10922070.

It is an arithmetic number, because the mean of its divisors is an integer number (10922070).

Almost surely, 2^21844139 is an apocalyptic number.

21844139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21844139 is an equidigital number, since it uses as much as digits as its factorization.

21844139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 32.

The square root of 21844139 is about 4673.7713893600. The cubic root of 21844139 is about 279.5406541586.

The spelling of 21844139 in words is "twenty-one million, eight hundred forty-four thousand, one hundred thirty-nine".