21427369 has 2 divisors, whose sum is σ = 21427370. Its totient is φ = 21427368.

The previous prime is 21427349. The next prime is 21427381. The reversal of 21427369 is 96372412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12355225 + 9072144 = 3515^2 + 3012^2 .

It is a cyclic number.

It is not a de Polignac number, because 21427369 - 2¹⁵ = 21394601 is a prime.

It is a super-2 number, since 2×21427369² = 918264284524322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21427309) 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, 10713684 + 10713685.

It is an arithmetic number, because the mean of its divisors is an integer number (10713685).

Almost surely, 2^21427369 is an apocalyptic number.

It is an amenable number.

21427369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21427369 is an equidigital number, since it uses as much as digits as its factorization.

21427369 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 34.

The square root of 21427369 is about 4628.9706199111. The cubic root of 21427369 is about 277.7514167636.

The spelling of 21427369 in words is "twenty-one million, four hundred twenty-seven thousand, three hundred sixty-nine".