21899651 has 2 divisors, whose sum is σ = 21899652. Its totient is φ = 21899650.

The previous prime is 21899641. The next prime is 21899677. The reversal of 21899651 is 15699812.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21899651 - 2¹⁸ = 21637507 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21899599 and 21899608.

It is not a weakly prime, because it can be changed into another prime (21899641) 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, 10949825 + 10949826.

It is an arithmetic number, because the mean of its divisors is an integer number (10949826).

Almost surely, 2^21899651 is an apocalyptic number.

21899651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21899651 is an equidigital number, since it uses as much as digits as its factorization.

21899651 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 41.

The square root of 21899651 is about 4679.7062942027. The cubic root of 21899651 is about 279.7772505634. Note that the first 3 decimals are identical.

The spelling of 21899651 in words is "twenty-one million, eight hundred ninety-nine thousand, six hundred fifty-one".