21123936 has 96 divisors (see below), whose sum is σ = 64350720. Its totient is φ = 6728832.

The previous prime is 21123917. The next prime is 21123983. The reversal of 21123936 is 63932112.

It is a tau number, because it is divible by the number of its divisors (96).

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19341 + ... + 20403.

It is an arithmetic number, because the mean of its divisors is an integer number (670320).

Almost surely, 2^21123936 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 21123936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32175360).

21123936 is an abundant number, since it is smaller than the sum of its proper divisors (43226784).

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

21123936 is a wasteful number, since it uses less digits than its factorization.

21123936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1105 (or 1091 counting only the distinct ones).

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

The square root of 21123936 is about 4596.0783283143. The cubic root of 21123936 is about 276.4340994885.

The spelling of 21123936 in words is "twenty-one million, one hundred twenty-three thousand, nine hundred thirty-six".