21819330 has 96 divisors (see below), whose sum is σ = 64746864. Its totient is φ = 5050368.

The previous prime is 21819323. The next prime is 21819331. The reversal of 21819330 is 3391812.

It can be written as a sum of positive squares in 8 ways, for example, as 6066369 + 15752961 = 2463^2 + 3969^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21819294 and 21819303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21819331) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 19342 + ... + 20438.

Almost surely, 2^21819330 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21819330, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32373432).

21819330 is an abundant number, since it is smaller than the sum of its proper divisors (42927534).

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

21819330 is a wasteful number, since it uses less digits than its factorization.

21819330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1140 (or 1137 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21819330 is about 4671.1165688730. The cubic root of 21819330 is about 279.4347866881.

It can be divided in two parts, 2181 and 9330, that added together give a palindrome (11511).

The spelling of 21819330 in words is "twenty-one million, eight hundred nineteen thousand, three hundred thirty".