21307104 has 192 divisors, whose sum is σ = 76769280. Its totient is φ = 5598720.

The previous prime is 21307093. The next prime is 21307109. The reversal of 21307104 is 40170312.

Added to its reverse (40170312) it gives a triangular number (61477416 = T₁₁₀₈₈).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21307109) 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 31 ways as a sum of consecutive naturals, for example, 78489 + ... + 78759.

It is an arithmetic number, because the mean of its divisors is an integer number (399840).

Almost surely, 2^21307104 is an apocalyptic number.

21307104 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 21307104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38384640).

21307104 is an abundant number, since it is smaller than the sum of its proper divisors (55462176).

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

21307104 is a wasteful number, since it uses less digits than its factorization.

21307104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310 (or 296 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21307104 is about 4615.9618715930. The cubic root of 21307104 is about 277.2307980998.

Adding to 21307104 its reverse (40170312), we get a palindrome (61477416).

The spelling of 21307104 in words is "twenty-one million, three hundred seven thousand, one hundred four".