21672420 has 96 divisors (see below), whose sum is σ = 75672576. Its totient is φ = 4502400.

The previous prime is 21672403. The next prime is 21672421. The reversal of 21672420 is 2427612.

It is not an unprimeable number, because it can be changed into a prime (21672421) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2275 + ... + 6965.

It is an arithmetic number, because the mean of its divisors is an integer number (788256).

Almost surely, 2^21672420 is an apocalyptic number.

21672420 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 21672420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37836288).

21672420 is an abundant number, since it is smaller than the sum of its proper divisors (54000156).

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

21672420 is a wasteful number, since it uses less digits than its factorization.

21672420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4721 (or 4719 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 21672420 is about 4655.3646473719. The cubic root of 21672420 is about 278.8062271368.

The spelling of 21672420 in words is "twenty-one million, six hundred seventy-two thousand, four hundred twenty".