21366123 has 4 divisors (see below), whose sum is σ = 28488168. Its totient is φ = 14244080.

The previous prime is 21366113. The next prime is 21366133. The reversal of 21366123 is 32166312.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21366113) and next prime (21366133).

It is a cyclic number.

It is not a de Polignac number, because 21366123 - 2⁵ = 21366091 is a prime.

It is a super-2 number, since 2×21366123² = 913022424102258, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21366093 and 21366102.

It is not an unprimeable number, because it can be changed into a prime (21366113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3561018 + ... + 3561023.

It is an arithmetic number, because the mean of its divisors is an integer number (7122042).

Almost surely, 2^21366123 is an apocalyptic number.

21366123 is a deficient number, since it is larger than the sum of its proper divisors (7122045).

21366123 is an equidigital number, since it uses as much as digits as its factorization.

21366123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7122044.

The product of its digits is 1296, while the sum is 24.

The square root of 21366123 is about 4622.3503761615. The cubic root of 21366123 is about 277.4865312836.

The spelling of 21366123 in words is "twenty-one million, three hundred sixty-six thousand, one hundred twenty-three".