21872304 has 60 divisors (see below), whose sum is σ = 61607416. Its totient is φ = 7243776.

The previous prime is 21872281. The next prime is 21872309. The reversal of 21872304 is 40327812.

21872304 = 236² + 237² + ... + 428².

It is not an unprimeable number, because it can be changed into a prime (21872309) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27399 + ... + 28185.

Almost surely, 2^21872304 is an apocalyptic number.

21872304 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 21872304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30803708).

21872304 is an abundant number, since it is smaller than the sum of its proper divisors (39735112).

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

21872304 is a wasteful number, since it uses less digits than its factorization.

With its successor (21872305) it forms a Ruth-Aaron pair, since the sum of their distinct prime factors is the same (985).

21872304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 994 (or 985 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21872304 is about 4676.7835100633. The cubic root of 21872304 is about 279.6607455802.

The spelling of 21872304 in words is "twenty-one million, eight hundred seventy-two thousand, three hundred four".