21035904 has 64 divisors (see below), whose sum is σ = 57834000. Its totient is φ = 6766592.

The previous prime is 21035897. The next prime is 21035909. The reversal of 21035904 is 40953012.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21035909) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10192 + ... + 12080.

Almost surely, 2^21035904 is an apocalyptic number.

21035904 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 21035904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28917000).

21035904 is an abundant number, since it is smaller than the sum of its proper divisors (36798096).

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

21035904 is a wasteful number, since it uses less digits than its factorization.

21035904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1935 (or 1923 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21035904 is about 4586.4914695222. The cubic root of 21035904 is about 276.0495605182.

Adding to 21035904 its reverse (40953012), we get a palindrome (61988916).

The spelling of 21035904 in words is "twenty-one million, thirty-five thousand, nine hundred four".