21355404 has 96 divisors (see below), whose sum is σ = 60211200. Its totient is φ = 5762880.

The previous prime is 21355403. The next prime is 21355409. The reversal of 21355404 is 40455312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 153567 + ... + 153705.

It is an arithmetic number, because the mean of its divisors is an integer number (627200).

Almost surely, 2^21355404 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 21355404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30105600).

21355404 is an abundant number, since it is smaller than the sum of its proper divisors (38855796).

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

21355404 is a wasteful number, since it uses less digits than its factorization.

21355404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243 (or 241 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 21355404 is about 4621.1907556386. The cubic root of 21355404 is about 277.4401201860.

The spelling of 21355404 in words is "twenty-one million, three hundred fifty-five thousand, four hundred four".