21884521 has 2 divisors, whose sum is σ = 21884522. Its totient is φ = 21884520.

The previous prime is 21884509. The next prime is 21884537. The reversal of 21884521 is 12548812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21715600 + 168921 = 4660^2 + 411^2 .

It is a cyclic number.

It is not a de Polignac number, because 21884521 - 2¹¹ = 21882473 is a prime.

It is equal to p_1382386 and since 21884521 and 1382386 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 (21884591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10942260 + 10942261.

It is an arithmetic number, because the mean of its divisors is an integer number (10942261).

Almost surely, 2^21884521 is an apocalyptic number.

It is an amenable number.

21884521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21884521 is an equidigital number, since it uses as much as digits as its factorization.

21884521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5120, while the sum is 31.

The square root of 21884521 is about 4678.0894604528. The cubic root of 21884521 is about 279.7128050157.

The spelling of 21884521 in words is "twenty-one million, eight hundred eighty-four thousand, five hundred twenty-one".