21919188 has 48 divisors (see below), whose sum is σ = 54613440. Its totient is φ = 6818304.

The previous prime is 21919181. The next prime is 21919189. The reversal of 21919188 is 88191912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21919181) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27970 + ... + 28742.

It is an arithmetic number, because the mean of its divisors is an integer number (1137780).

Almost surely, 2^21919188 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 21919188, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27306720).

21919188 is an abundant number, since it is smaller than the sum of its proper divisors (32694252).

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

21919188 is a wasteful number, since it uses less digits than its factorization.

21919188 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 936 (or 934 counting only the distinct ones).

The product of its digits is 10368, while the sum is 39.

The square root of 21919188 is about 4681.7932461825. The cubic root of 21919188 is about 279.8604236318.

The spelling of 21919188 in words is "twenty-one million, nine hundred nineteen thousand, one hundred eighty-eight".