21645360 has 160 divisors (see below), whose sum is σ = 81423360. Its totient is φ = 5241600.

The previous prime is 21645343. The next prime is 21645373. The reversal of 21645360 is 6354612.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23305 + ... + 24215.

It is an arithmetic number, because the mean of its divisors is an integer number (508896).

Almost surely, 2^21645360 is an apocalyptic number.

21645360 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 21645360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40711680).

21645360 is an abundant number, since it is smaller than the sum of its proper divisors (59778000).

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

21645360 is a wasteful number, since it uses less digits than its factorization.

21645360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944 (or 932 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 21645360 is about 4652.4574151732. The cubic root of 21645360 is about 278.6901404441.

Adding to 21645360 its reverse (6354612), we get a palindrome (27999972).

The spelling of 21645360 in words is "twenty-one million, six hundred forty-five thousand, three hundred sixty".