21396123 has 32 divisors (see below), whose sum is σ = 36710400. Its totient is φ = 12063168.

The previous prime is 21396119. The next prime is 21396161. The reversal of 21396123 is 32169312.

It is not a de Polignac number, because 21396123 - 2² = 21396119 is a prime.

It is a super-2 number, since 2×21396123² = 915588158862258, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21396103) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14215 + ... + 15647.

It is an arithmetic number, because the mean of its divisors is an integer number (1147200).

Almost surely, 2^21396123 is an apocalyptic number.

21396123 is a deficient number, since it is larger than the sum of its proper divisors (15314277).

21396123 is a wasteful number, since it uses less digits than its factorization.

21396123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1528 (or 1522 counting only the distinct ones).

The product of its digits is 1944, while the sum is 27.

The square root of 21396123 is about 4625.5943401902. The cubic root of 21396123 is about 277.6163427428.

The spelling of 21396123 in words is "twenty-one million, three hundred ninety-six thousand, one hundred twenty-three".