21022420 has 24 divisors (see below), whose sum is σ = 44249184. Its totient is φ = 8389536.

The previous prime is 21022411. The next prime is 21022427. The reversal of 21022420 is 2422012.

It is a self number, because there is not a number n which added to its sum of digits gives 21022420.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022427) 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, 10327 + ... + 12193.

It is an arithmetic number, because the mean of its divisors is an integer number (1843716).

Almost surely, 2^21022420 is an apocalyptic number.

21022420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21022420 is an abundant number, since it is smaller than the sum of its proper divisors (23226764).

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

21022420 is a wasteful number, since it uses less digits than its factorization.

21022420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2439 (or 2437 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 21022420 is about 4585.0212649452. The cubic root of 21022420 is about 275.9905653850.

Adding to 21022420 its reverse (2422012), we get a palindrome (23444432).

The spelling of 21022420 in words is "twenty-one million, twenty-two thousand, four hundred twenty".