21019220 has 12 divisors (see below), whose sum is σ = 44140404. Its totient is φ = 8407680.

The previous prime is 21019189. The next prime is 21019231. The reversal of 21019220 is 2291012.

It can be written as a sum of positive squares in 2 ways, for example, as 14227984 + 6791236 = 3772^2 + 2606^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525461 + ... + 525500.

It is an arithmetic number, because the mean of its divisors is an integer number (3678367).

Almost surely, 2^21019220 is an apocalyptic number.

21019220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21019220 is an abundant number, since it is smaller than the sum of its proper divisors (23121184).

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

21019220 is a wasteful number, since it uses less digits than its factorization.

21019220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1050970 (or 1050968 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21019220 is about 4584.6722892700. The cubic root of 21019220 is about 275.9765610565.

The spelling of 21019220 in words is "twenty-one million, nineteen thousand, two hundred twenty".