21634213 has 2 divisors, whose sum is σ = 21634214. Its totient is φ = 21634212.

The previous prime is 21634181. The next prime is 21634253. The reversal of 21634213 is 31243612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16785409 + 4848804 = 4097^2 + 2202^2 .

It is a cyclic number.

It is not a de Polignac number, because 21634213 - 2⁵ = 21634181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21634253) 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, 10817106 + 10817107.

It is an arithmetic number, because the mean of its divisors is an integer number (10817107).

Almost surely, 2^21634213 is an apocalyptic number.

It is an amenable number.

21634213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21634213 is an equidigital number, since it uses as much as digits as its factorization.

21634213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 22.

The square root of 21634213 is about 4651.2592918477. The cubic root of 21634213 is about 278.6422919687.

Adding to 21634213 its reverse (31243612), we get a palindrome (52877825).

The spelling of 21634213 in words is "twenty-one million, six hundred thirty-four thousand, two hundred thirteen".