21619872 has 120 divisors (see below), whose sum is σ = 67082400. Its totient is φ = 6811776.

The previous prime is 21619867. The next prime is 21619879. The reversal of 21619872 is 27891612.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21619879) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 49029 + ... + 49467.

It is an arithmetic number, because the mean of its divisors is an integer number (559020).

Almost surely, 2^21619872 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 21619872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33541200).

21619872 is an abundant number, since it is smaller than the sum of its proper divisors (45462528).

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

21619872 is a wasteful number, since it uses less digits than its factorization.

21619872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 480 (or 463 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21619872 is about 4649.7174107681. The cubic root of 21619872 is about 278.5807090737.

The spelling of 21619872 in words is "twenty-one million, six hundred nineteen thousand, eight hundred seventy-two".