21000000012220 has 48 divisors (see below), whose sum is σ = 44697644681760. Its totient is φ = 8286463696896.

The previous prime is 21000000012181. The next prime is 21000000012259. The reversal of 21000000012220 is 2221000000012.

It is an interprime number because it is at equal distance from previous prime (21000000012181) and next prime (21000000012259).

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21000000012197 and 21000000012206.

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, 8281485 + ... + 10515844.

It is an arithmetic number, because the mean of its divisors is an integer number (931200930870).

Almost surely, 2^{21000000012220} is an apocalyptic number.

21000000012220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000000012220 is an abundant number, since it is smaller than the sum of its proper divisors (23697644669540).

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

21000000012220 is a wasteful number, since it uses less digits than its factorization.

21000000012220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18798094 (or 18798092 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21000000012220 its reverse (2221000000012), we get a palindrome (23221000012232).

The spelling of 21000000012220 in words is "twenty-one trillion, twelve thousand, two hundred twenty".