21213089 has 2 divisors, whose sum is σ = 21213090. Its totient is φ = 21213088.

The previous prime is 21213047. The next prime is 21213097. The reversal of 21213089 is 98031212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17181025 + 4032064 = 4145^2 + 2008^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213089 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21213029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606544 + 10606545.

It is an arithmetic number, because the mean of its divisors is an integer number (10606545).

Almost surely, 2^21213089 is an apocalyptic number.

It is an amenable number.

21213089 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213089 is an equidigital number, since it uses as much as digits as its factorization.

21213089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21213089 is about 4605.7669285364. The cubic root of 21213089 is about 276.8224478729.

The spelling of 21213089 in words is "twenty-one million, two hundred thirteen thousand, eighty-nine".