21866280 has 64 divisors (see below), whose sum is σ = 67011840. Its totient is φ = 5705472.

The previous prime is 21866249. The next prime is 21866303. The reversal of 21866280 is 8266812.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3702 + ... + 7578.

It is an arithmetic number, because the mean of its divisors is an integer number (1047060).

Almost surely, 2^21866280 is an apocalyptic number.

21866280 is a gapful number since it is divisible by the number (20) 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 21866280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33505920).

21866280 is an abundant number, since it is smaller than the sum of its proper divisors (45145560).

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

21866280 is a wasteful number, since it uses less digits than its factorization.

21866280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3938 (or 3934 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 21866280 is about 4676.1394333360. The cubic root of 21866280 is about 279.6350688001.

The spelling of 21866280 in words is "twenty-one million, eight hundred sixty-six thousand, two hundred eighty".