21291367 has 2 divisors, whose sum is σ = 21291368. Its totient is φ = 21291366.

The previous prime is 21291359. The next prime is 21291373. The reversal of 21291367 is 76319212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21291367 - 2³ = 21291359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21291337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10645683 + 10645684.

It is an arithmetic number, because the mean of its divisors is an integer number (10645684).

Almost surely, 2^21291367 is an apocalyptic number.

21291367 is a deficient number, since it is larger than the sum of its proper divisors (1).

21291367 is an equidigital number, since it uses as much as digits as its factorization.

21291367 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4536, while the sum is 31.

The square root of 21291367 is about 4614.2569282605. The cubic root of 21291367 is about 277.1625289191.

The spelling of 21291367 in words is "twenty-one million, two hundred ninety-one thousand, three hundred sixty-seven".