21366139 has 2 divisors, whose sum is σ = 21366140. Its totient is φ = 21366138.

The previous prime is 21366133. The next prime is 21366173. The reversal of 21366139 is 93166312.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21366139 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21366139.

It is not a weakly prime, because it can be changed into another prime (21366133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10683069 + 10683070.

It is an arithmetic number, because the mean of its divisors is an integer number (10683070).

Almost surely, 2^21366139 is an apocalyptic number.

21366139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21366139 is an equidigital number, since it uses as much as digits as its factorization.

21366139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5832, while the sum is 31.

The square root of 21366139 is about 4622.3521068824. The cubic root of 21366139 is about 277.4866005488.

The spelling of 21366139 in words is "twenty-one million, three hundred sixty-six thousand, one hundred thirty-nine".