21616139 has 2 divisors, whose sum is σ = 21616140. Its totient is φ = 21616138.

The previous prime is 21616123. The next prime is 21616141. The reversal of 21616139 is 93161612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21616139 - 2⁴ = 21616123 is a prime.

Together with 21616141, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21616169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808069 + 10808070.

It is an arithmetic number, because the mean of its divisors is an integer number (10808070).

Almost surely, 2^21616139 is an apocalyptic number.

21616139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21616139 is an equidigital number, since it uses as much as digits as its factorization.

21616139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1944, while the sum is 29.

The square root of 21616139 is about 4649.3159711940. The cubic root of 21616139 is about 278.5646744175.

The spelling of 21616139 in words is "twenty-one million, six hundred sixteen thousand, one hundred thirty-nine".