21036139 has 2 divisors, whose sum is σ = 21036140. Its totient is φ = 21036138.

The previous prime is 21036137. The next prime is 21036143. The reversal of 21036139 is 93163012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21036139 - 2¹ = 21036137 is a prime.

Together with 21036137, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21036131) 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, 10518069 + 10518070.

It is an arithmetic number, because the mean of its divisors is an integer number (10518070).

Almost surely, 2^21036139 is an apocalyptic number.

21036139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21036139 is an equidigital number, since it uses as much as digits as its factorization.

21036139 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 21036139 is about 4586.5170881618. The cubic root of 21036139 is about 276.0505884656.

The spelling of 21036139 in words is "twenty-one million, thirty-six thousand, one hundred thirty-nine".