21020012220 has 48 divisors (see below), whose sum is σ = 59164213248. Its totient is φ = 5575986240.

The previous prime is 21020012207. The next prime is 21020012231. The reversal of 21020012220 is 2221002012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21020012196 and 21020012205.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 905644 + ... + 928563.

It is an arithmetic number, because the mean of its divisors is an integer number (1232587776).

Almost surely, 2^21020012220 is an apocalyptic number.

21020012220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020012220 is an abundant number, since it is smaller than the sum of its proper divisors (38144201028).

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

21020012220 is a wasteful number, since it uses less digits than its factorization.

21020012220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1834410 (or 1834408 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

Adding to 21020012220 its reverse (2221002012), we get a palindrome (23241014232).

The spelling of 21020012220 in words is "twenty-one billion, twenty million, twelve thousand, two hundred twenty".