21723936 has 96 divisors (see below), whose sum is σ = 62375040. Its totient is φ = 6619392.

The previous prime is 21723931. The next prime is 21723959. The reversal of 21723936 is 63932712.

It is a happy number.

21723936 is a nontrivial binomial coefficient, being equal to C(6592, 2).

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

It is a junction number, because it is equal to n+sod(n) for n = 21723897 and 21723906.

It is not an unprimeable number, because it can be changed into a prime (21723931) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 210861 + ... + 210963.

It is an arithmetic number, because the mean of its divisors is an integer number (649740).

Almost surely, 2^21723936 is an apocalyptic number.

21723936 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21723936 is the 6591-st triangular number and also the 3296-th hexagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21723936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31187520).

21723936 is an abundant number, since it is smaller than the sum of its proper divisors (40651104).

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

21723936 is a wasteful number, since it uses less digits than its factorization.

21723936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155 (or 121 counting only the distinct ones).

The product of its digits is 13608, while the sum is 33.

The square root of 21723936 is about 4660.8943347817. The cubic root of 21723936 is about 279.0269626182.

The spelling of 21723936 in words is "twenty-one million, seven hundred twenty-three thousand, nine hundred thirty-six".