21107304 has 40 divisors (see below), whose sum is σ = 59121810. Its totient is φ = 7035552.

The previous prime is 21107291. The next prime is 21107341. The reversal of 21107304 is 40370112.

Added to its reverse (40370112) it gives a triangular number (61477416 = T₁₁₀₈₈).

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 39204 = 4590^2 + 198^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 15639 + ... + 16934.

Almost surely, 2^21107304 is an apocalyptic number.

21107304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21107304 is an abundant number, since it is smaller than the sum of its proper divisors (38014506).

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

21107304 is a wasteful number, since it uses less digits than its factorization.

21107304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32591 (or 32578 counting only the distinct ones).

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

The square root of 21107304 is about 4594.2686033797. The cubic root of 21107304 is about 276.3615300089.

Adding to 21107304 its reverse (40370112), we get a palindrome (61477416).

The spelling of 21107304 in words is "twenty-one million, one hundred seven thousand, three hundred four".