21634404 has 96 divisors (see below), whose sum is σ = 60383232. Its totient is φ = 5952000.

The previous prime is 21634399. The next prime is 21634411. The reversal of 21634404 is 40443612.

21634404 = 93² + 94² + ... + 403².

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 69409 + ... + 69719.

It is an arithmetic number, because the mean of its divisors is an integer number (628992).

Almost surely, 2^21634404 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 21634404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30191616).

21634404 is an abundant number, since it is smaller than the sum of its proper divisors (38748828).

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

21634404 is a wasteful number, since it uses less digits than its factorization.

21634404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 377 (or 375 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

The square root of 21634404 is about 4651.2798238764. The cubic root of 21634404 is about 278.6431119742.

The spelling of 21634404 in words is "twenty-one million, six hundred thirty-four thousand, four hundred four".