21123588 has 36 divisors (see below), whose sum is σ = 52366832. Its totient is φ = 6625920.

The previous prime is 21123533. The next prime is 21123589. The reversal of 21123588 is 88532112.

It is not an unprimeable number, because it can be changed into a prime (21123589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 423 + ... + 6513.

Almost surely, 2^21123588 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21123588, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26183416).

21123588 is an abundant number, since it is smaller than the sum of its proper divisors (31243244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123588 is a wasteful number, since it uses less digits than its factorization.

21123588 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6132 (or 6113 counting only the distinct ones).

The product of its digits is 3840, while the sum is 30.

The square root of 21123588 is about 4596.0404697957. The cubic root of 21123588 is about 276.4325814698.

The spelling of 21123588 in words is "twenty-one million, one hundred twenty-three thousand, five hundred eighty-eight".