21775289 has 2 divisors, whose sum is σ = 21775290. Its totient is φ = 21775288.

The previous prime is 21775267. The next prime is 21775301. The reversal of 21775289 is 98257712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13935289 + 7840000 = 3733^2 + 2800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21775289 - 2²⁴ = 4998073 is a prime.

It is a super-2 number, since 2×21775289² = 948326422067042, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21775219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10887644 + 10887645.

It is an arithmetic number, because the mean of its divisors is an integer number (10887645).

Almost surely, 2^21775289 is an apocalyptic number.

It is an amenable number.

21775289 is a deficient number, since it is larger than the sum of its proper divisors (1).

21775289 is an equidigital number, since it uses as much as digits as its factorization.

21775289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 70560, while the sum is 41.

The square root of 21775289 is about 4666.4000042860. The cubic root of 21775289 is about 279.2466526380.

The spelling of 21775289 in words is "twenty-one million, seven hundred seventy-five thousand, two hundred eighty-nine".