21836651 has 2 divisors, whose sum is σ = 21836652. Its totient is φ = 21836650.

The previous prime is 21836629. The next prime is 21836669. The reversal of 21836651 is 15663812.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21836651 - 2¹⁸ = 21574507 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21836611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10918325 + 10918326.

It is an arithmetic number, because the mean of its divisors is an integer number (10918326).

Almost surely, 2^21836651 is an apocalyptic number.

21836651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21836651 is an equidigital number, since it uses as much as digits as its factorization.

21836651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 32.

The square root of 21836651 is about 4672.9702545597. The cubic root of 21836651 is about 279.5087090582.

The spelling of 21836651 in words is "twenty-one million, eight hundred thirty-six thousand, six hundred fifty-one".