21366259 has 2 divisors, whose sum is σ = 21366260. Its totient is φ = 21366258.

The previous prime is 21366239. The next prime is 21366271. The reversal of 21366259 is 95266312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21366259 - 2¹³ = 21358067 is a prime.

It is not a weakly prime, because it can be changed into another prime (21366239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10683129 + 10683130.

It is an arithmetic number, because the mean of its divisors is an integer number (10683130).

Almost surely, 2^21366259 is an apocalyptic number.

21366259 is a deficient number, since it is larger than the sum of its proper divisors (1).

21366259 is an equidigital number, since it uses as much as digits as its factorization.

21366259 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 34.

The square root of 21366259 is about 4622.3650872686. The cubic root of 21366259 is about 277.4871200363.

The spelling of 21366259 in words is "twenty-one million, three hundred sixty-six thousand, two hundred fifty-nine".