21684360 has 64 divisors (see below), whose sum is σ = 65577600. Its totient is φ = 5735936.

The previous prime is 21684353. The next prime is 21684371. The reversal of 21684360 is 6348612.

It is a super-2 number, since 2×21684360² = 940422937219200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 15781 + ... + 17099.

It is an arithmetic number, because the mean of its divisors is an integer number (1024650).

Almost surely, 2^21684360 is an apocalyptic number.

21684360 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 21684360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32788800).

21684360 is an abundant number, since it is smaller than the sum of its proper divisors (43893240).

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

21684360 is a wasteful number, since it uses less digits than its factorization.

21684360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1470 (or 1466 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 21684360 is about 4656.6468622819. The cubic root of 21684360 is about 278.8574187004.

The spelling of 21684360 in words is "twenty-one million, six hundred eighty-four thousand, three hundred sixty".