21210121220 has 24 divisors (see below), whose sum is σ = 45296193600. Its totient is φ = 8340250592.

The previous prime is 21210121187. The next prime is 21210121223. The reversal of 21210121220 is 2212101212.

It is a junction number, because it is equal to n+sod(n) for n = 21210121195 and 21210121204.

It is not an unprimeable number, because it can be changed into a prime (21210121223) 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, 8986160 + ... + 8988519.

It is an arithmetic number, because the mean of its divisors is an integer number (1887341400).

Almost surely, 2^21210121220 is an apocalyptic number.

21210121220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210121220 is an abundant number, since it is smaller than the sum of its proper divisors (24086072380).

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

21210121220 is a wasteful number, since it uses less digits than its factorization.

21210121220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17974747 (or 17974745 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21210121220 its reverse (2212101212), we get a palindrome (23422222432).

The spelling of 21210121220 in words is "twenty-one billion, two hundred ten million, one hundred twenty-one thousand, two hundred twenty".