21669960 has 128 divisors (see below), whose sum is σ = 72576000. Its totient is φ = 5139456.

The previous prime is 21669959. The next prime is 21670003. The reversal of 21669960 is 6996612.

It is a Harshad number since it is a multiple of its sum of digits (39).

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, 45001 + ... + 45479.

It is an arithmetic number, because the mean of its divisors is an integer number (567000).

Almost surely, 2^21669960 is an apocalyptic number.

21669960 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 21669960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36288000).

21669960 is an abundant number, since it is smaller than the sum of its proper divisors (50906040).

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

21669960 is a wasteful number, since it uses less digits than its factorization.

21669960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535 (or 531 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 39.

The square root of 21669960 is about 4655.1004285622. The cubic root of 21669960 is about 278.7956777954.

The spelling of 21669960 in words is "twenty-one million, six hundred sixty-nine thousand, nine hundred sixty".