21611087 has 2 divisors, whose sum is σ = 21611088. Its totient is φ = 21611086.

The previous prime is 21611041. The next prime is 21611143. The reversal of 21611087 is 78011612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21611087 - 2¹⁶ = 21545551 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21611017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10805543 + 10805544.

It is an arithmetic number, because the mean of its divisors is an integer number (10805544).

Almost surely, 2^21611087 is an apocalyptic number.

21611087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21611087 is an equidigital number, since it uses as much as digits as its factorization.

21611087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 21611087 is about 4648.7726337174. The cubic root of 21611087 is about 278.5429712141.

Adding to 21611087 its reverse (78011612), we get a palindrome (99622699).

The spelling of 21611087 in words is "twenty-one million, six hundred eleven thousand, eighty-seven".