21869123 has 4 divisors (see below), whose sum is σ = 23155560. Its totient is φ = 20582688.

The previous prime is 21869119. The next prime is 21869129. The reversal of 21869123 is 32196812.

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 21869123 - 2² = 21869119 is a prime.

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 21869123.

It is not an unprimeable number, because it can be changed into a prime (21869129) 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, 643193 + ... + 643226.

It is an arithmetic number, because the mean of its divisors is an integer number (5788890).

Almost surely, 2^21869123 is an apocalyptic number.

21869123 is a deficient number, since it is larger than the sum of its proper divisors (1286437).

21869123 is a wasteful number, since it uses less digits than its factorization.

21869123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1286436.

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

The square root of 21869123 is about 4676.4434135355. The cubic root of 21869123 is about 279.6471874298.

The spelling of 21869123 in words is "twenty-one million, eight hundred sixty-nine thousand, one hundred twenty-three".