21002011220 has 24 divisors (see below), whose sum is σ = 44247898464. Its totient is φ = 8373437856.

The previous prime is 21002011213. The next prime is 21002011231. The reversal of 21002011220 is 2211020012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1704122 + ... + 1716401.

It is an arithmetic number, because the mean of its divisors is an integer number (1843662436).

Almost surely, 2^21002011220 is an apocalyptic number.

21002011220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002011220 is an abundant number, since it is smaller than the sum of its proper divisors (23245887244).

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

21002011220 is a wasteful number, since it uses less digits than its factorization.

21002011220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3420839 (or 3420837 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21002011220 its reverse (2211020012), we get a palindrome (23213031232).

The spelling of 21002011220 in words is "twenty-one billion, two million, eleven thousand, two hundred twenty".