21013087 has 2 divisors, whose sum is σ = 21013088. Its totient is φ = 21013086.

The previous prime is 21013073. The next prime is 21013093. The reversal of 21013087 is 78031012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21013087 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21013787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506543 + 10506544.

It is an arithmetic number, because the mean of its divisors is an integer number (10506544).

Almost surely, 2^21013087 is an apocalyptic number.

21013087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013087 is an equidigital number, since it uses as much as digits as its factorization.

21013087 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 21013087 is about 4584.0033813251. The cubic root of 21013087 is about 275.9497169127.

Adding to 21013087 its reverse (78031012), we get a palindrome (99044099).

The spelling of 21013087 in words is "twenty-one million, thirteen thousand, eighty-seven".