21290569 has 2 divisors, whose sum is σ = 21290570. Its totient is φ = 21290568.

The previous prime is 21290567. The next prime is 21290593. The reversal of 21290569 is 96509212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21040569 + 250000 = 4587^2 + 500^2 .

It is a cyclic number.

It is not a de Polignac number, because 21290569 - 2¹ = 21290567 is a prime.

It is a super-2 number, since 2×21290569² = 906576656687522, which contains 22 as substring.

Together with 21290567, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21290567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10645284 + 10645285.

It is an arithmetic number, because the mean of its divisors is an integer number (10645285).

Almost surely, 2^21290569 is an apocalyptic number.

It is an amenable number.

21290569 is a deficient number, since it is larger than the sum of its proper divisors (1).

21290569 is an equidigital number, since it uses as much as digits as its factorization.

21290569 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 21290569 is about 4614.1704563226. The cubic root of 21290569 is about 277.1590661939.

The spelling of 21290569 in words is "twenty-one million, two hundred ninety thousand, five hundred sixty-nine".