21907087 has 2 divisors, whose sum is σ = 21907088. Its totient is φ = 21907086.

The previous prime is 21907027. The next prime is 21907097. The reversal of 21907087 is 78070912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21907087 - 2¹⁹ = 21382799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21907007) 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, 10953543 + 10953544.

It is an arithmetic number, because the mean of its divisors is an integer number (10953544).

Almost surely, 2^21907087 is an apocalyptic number.

21907087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21907087 is an equidigital number, since it uses as much as digits as its factorization.

21907087 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 34.

The square root of 21907087 is about 4680.5007210768. The cubic root of 21907087 is about 279.8089129890.

Adding to 21907087 its reverse (78070912), we get a palindrome (99977999).

The spelling of 21907087 in words is "twenty-one million, nine hundred seven thousand, eighty-seven".