21897611 has 2 divisors, whose sum is σ = 21897612. Its totient is φ = 21897610.

The previous prime is 21897569. The next prime is 21897637. The reversal of 21897611 is 11679812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21897611 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21897661) 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, 10948805 + 10948806.

It is an arithmetic number, because the mean of its divisors is an integer number (10948806).

Almost surely, 2^21897611 is an apocalyptic number.

21897611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21897611 is an equidigital number, since it uses as much as digits as its factorization.

21897611 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 35.

The square root of 21897611 is about 4679.4883267298. The cubic root of 21897611 is about 279.7685630077.

The spelling of 21897611 in words is "twenty-one million, eight hundred ninety-seven thousand, six hundred eleven".