21654660 has 48 divisors (see below), whose sum is σ = 61217856. Its totient is φ = 5718912.

The previous prime is 21654649. The next prime is 21654667. The reversal of 21654660 is 6645612.

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

It is not an unprimeable number, because it can be changed into a prime (21654667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4734 + ... + 8106.

It is an arithmetic number, because the mean of its divisors is an integer number (1275372).

Almost surely, 2^21654660 is an apocalyptic number.

21654660 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 21654660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30608928).

21654660 is an abundant number, since it is smaller than the sum of its proper divisors (39563196).

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

21654660 is a wasteful number, since it uses less digits than its factorization.

21654660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3492 (or 3490 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 21654660 is about 4653.4567796424. The cubic root of 21654660 is about 278.7300481071.

The spelling of 21654660 in words is "twenty-one million, six hundred fifty-four thousand, six hundred sixty".