21123868 has 12 divisors (see below), whose sum is σ = 37753632. Its totient is φ = 10337120.

The previous prime is 21123863. The next prime is 21123871. The reversal of 21123868 is 86832112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123863) 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, 55993 + ... + 56368.

It is an arithmetic number, because the mean of its divisors is an integer number (3146136).

Almost surely, 2^21123868 is an apocalyptic number.

It is an amenable number.

21123868 is a deficient number, since it is larger than the sum of its proper divisors (16629764).

21123868 is a wasteful number, since it uses less digits than its factorization.

21123868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112412 (or 112410 counting only the distinct ones).

The product of its digits is 4608, while the sum is 31.

The square root of 21123868 is about 4596.0709306972. The cubic root of 21123868 is about 276.4338028655.

The spelling of 21123868 in words is "twenty-one million, one hundred twenty-three thousand, eight hundred sixty-eight".