21896123 has 4 divisors (see below), whose sum is σ = 22090008. Its totient is φ = 21702240.

The previous prime is 21896099. The next prime is 21896167. The reversal of 21896123 is 32169812.

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

It is a cyclic number.

It is not a de Polignac number, because 21896123 - 2¹⁶ = 21830587 is a prime.

It is a super-2 number, since 2×21896123² = 958880404862258, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21896123.

It is not an unprimeable number, because it can be changed into a prime (21895123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96773 + ... + 96998.

It is an arithmetic number, because the mean of its divisors is an integer number (5522502).

Almost surely, 2^21896123 is an apocalyptic number.

21896123 is a deficient number, since it is larger than the sum of its proper divisors (193885).

21896123 is a wasteful number, since it uses less digits than its factorization.

21896123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193884.

The product of its digits is 5184, while the sum is 32.

The square root of 21896123 is about 4679.3293322868. The cubic root of 21896123 is about 279.7622258620.

The spelling of 21896123 in words is "twenty-one million, eight hundred ninety-six thousand, one hundred twenty-three".