21022220 has 24 divisors (see below), whose sum is σ = 44445408. Its totient is φ = 8352000.

The previous prime is 21022219. The next prime is 21022223. The reversal of 21022220 is 2222012.

It is not an unprimeable number, because it can be changed into a prime (21022223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 461 + ... + 6500.

It is an arithmetic number, because the mean of its divisors is an integer number (1851892).

Almost surely, 2^21022220 is an apocalyptic number.

21022220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21022220 is an abundant number, since it is smaller than the sum of its proper divisors (23423188).

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

21022220 is a wasteful number, since it uses less digits than its factorization.

21022220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7121 (or 7119 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21022220 is about 4584.9994547437. Note that the first 3 decimals coincide. The cubic root of 21022220 is about 275.9896901561.

Adding to 21022220 its reverse (2222012), we get a palindrome (23244232).

The spelling of 21022220 in words is "twenty-one million, twenty-two thousand, two hundred twenty".