21666432 has 64 divisors (see below), whose sum is σ = 60955200. Its totient is φ = 6795264.

The previous prime is 21666397. The next prime is 21666443. The reversal of 21666432 is 23466612.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×21666432² = 938868551221248, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21666432.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4869 + ... + 8187.

It is an arithmetic number, because the mean of its divisors is an integer number (952425).

Almost surely, 2^21666432 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21666432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30477600).

21666432 is an abundant number, since it is smaller than the sum of its proper divisors (39288768).

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

21666432 is a wasteful number, since it uses less digits than its factorization.

21666432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3353 (or 3341 counting only the distinct ones).

The product of its digits is 10368, while the sum is 30.

The square root of 21666432 is about 4654.7214739445. The cubic root of 21666432 is about 278.7805471024.

The spelling of 21666432 in words is "twenty-one million, six hundred sixty-six thousand, four hundred thirty-two".