21596904 has 96 divisors (see below), whose sum is σ = 67878720. Its totient is φ = 6075648.

The previous prime is 21596903. The next prime is 21596921. The reversal of 21596904 is 40969512.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21596903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36499 + ... + 37085.

It is an arithmetic number, because the mean of its divisors is an integer number (707070).

Almost surely, 2^21596904 is an apocalyptic number.

21596904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21596904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33939360).

21596904 is an abundant number, since it is smaller than the sum of its proper divisors (46281816).

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

21596904 is a wasteful number, since it uses less digits than its factorization.

21596904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 679 (or 672 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 21596904 is about 4647.2469269450. The cubic root of 21596904 is about 278.4820234930.

It can be divided in two parts, 21596 and 904, that added together give a square (22500 = 150²).

The spelling of 21596904 in words is "twenty-one million, five hundred ninety-six thousand, nine hundred four".