21604104 has 32 divisors (see below), whose sum is σ = 60012000. Its totient is φ = 7201296.

The previous prime is 21604091. The next prime is 21604109. The reversal of 21604104 is 40140612.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21604109) 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, 49794 + ... + 50225.

It is an arithmetic number, because the mean of its divisors is an integer number (1875375).

Almost surely, 2^21604104 is an apocalyptic number.

21604104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21604104 is an abundant number, since it is smaller than the sum of its proper divisors (38407896).

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

21604104 is a wasteful number, since it uses less digits than its factorization.

21604104 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100034 (or 100024 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21604104 is about 4648.0215145802. The cubic root of 21604104 is about 278.5129669374.

Adding to 21604104 its reverse (40140612), we get a palindrome (61744716).

The spelling of 21604104 in words is "twenty-one million, six hundred four thousand, one hundred four".