21634579 has 2 divisors, whose sum is σ = 21634580. Its totient is φ = 21634578.

The previous prime is 21634573. The next prime is 21634607. The reversal of 21634579 is 97543612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21634579 - 2⁷ = 21634451 is a prime.

It is a Chen prime.

It is equal to p_1367569 and since 21634579 and 1367569 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21634573) 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, 10817289 + 10817290.

It is an arithmetic number, because the mean of its divisors is an integer number (10817290).

Almost surely, 2^21634579 is an apocalyptic number.

21634579 is a deficient number, since it is larger than the sum of its proper divisors (1).

21634579 is an equidigital number, since it uses as much as digits as its factorization.

21634579 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 37.

The square root of 21634579 is about 4651.2986358650. The cubic root of 21634579 is about 278.6438632839.

The spelling of 21634579 in words is "twenty-one million, six hundred thirty-four thousand, five hundred seventy-nine".