21919220 has 12 divisors (see below), whose sum is σ = 46030404. Its totient is φ = 8767680.

The previous prime is 21919213. The next prime is 21919223. The reversal of 21919220 is 2291912.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 12931216 + 8988004 = 3596^2 + 2998^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21919220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21919223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 547961 + ... + 548000.

It is an arithmetic number, because the mean of its divisors is an integer number (3835867).

Almost surely, 2^21919220 is an apocalyptic number.

21919220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21919220 is an abundant number, since it is smaller than the sum of its proper divisors (24111184).

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

21919220 is a wasteful number, since it uses less digits than its factorization.

21919220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1095970 (or 1095968 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 21919220 is about 4681.7966636752. The cubic root of 21919220 is about 279.8605598219.

It can be divided in two parts, 2191 and 9220, that added together give a palindrome (11411).

The spelling of 21919220 in words is "twenty-one million, nine hundred nineteen thousand, two hundred twenty".