21669180 has 72 divisors (see below), whose sum is σ = 65730672. Its totient is φ = 5331456.

The previous prime is 21669173. The next prime is 21669181. The reversal of 21669180 is 8196612.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21669181) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9072 + ... + 11208.

It is an arithmetic number, because the mean of its divisors is an integer number (912926).

Almost surely, 2^21669180 is an apocalyptic number.

21669180 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 21669180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32865336).

21669180 is an abundant number, since it is smaller than the sum of its proper divisors (44061492).

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

21669180 is a wasteful number, since it uses less digits than its factorization.

21669180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2175 (or 2160 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 21669180 is about 4655.0166487350. The cubic root of 21669180 is about 278.7923327156.

It can be divided in two parts, 216 and 69180, that added together give a palindrome (69396).

The spelling of 21669180 in words is "twenty-one million, six hundred sixty-nine thousand, one hundred eighty".