21021222120 has 32 divisors (see below), whose sum is σ = 63063666720. Its totient is φ = 5605659200.

The previous prime is 21021222119. The next prime is 21021222127. The reversal of 21021222120 is 2122212012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21021222120.

It is not an unprimeable number, because it can be changed into a prime (21021222127) 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, 87588306 + ... + 87588545.

It is an arithmetic number, because the mean of its divisors is an integer number (1970739585).

Almost surely, 2^21021222120 is an apocalyptic number.

21021222120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021222120 is an abundant number, since it is smaller than the sum of its proper divisors (42042444600).

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

21021222120 is a wasteful number, since it uses less digits than its factorization.

21021222120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175176865 (or 175176861 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21021222120 its reverse (2122212012), we get a palindrome (23143434132).

The spelling of 21021222120 in words is "twenty-one billion, twenty-one million, two hundred twenty-two thousand, one hundred twenty".