21392291 has 2 divisors, whose sum is σ = 21392292. Its totient is φ = 21392290.

The previous prime is 21392281. The next prime is 21392299. The reversal of 21392291 is 19229312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21392291 - 2¹⁰ = 21391267 is a prime.

It is a super-2 number, since 2×21392291² = 915260228457362, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21392299) 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, 10696145 + 10696146.

It is an arithmetic number, because the mean of its divisors is an integer number (10696146).

Almost surely, 2^21392291 is an apocalyptic number.

21392291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21392291 is an equidigital number, since it uses as much as digits as its factorization.

21392291 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 29.

The square root of 21392291 is about 4625.1801046013. The cubic root of 21392291 is about 277.5997682549.

The spelling of 21392291 in words is "twenty-one million, three hundred ninety-two thousand, two hundred ninety-one".