21002002120 has 32 divisors (see below), whose sum is σ = 51550369920. Its totient is φ = 7637091520.

The previous prime is 21002002111. The next prime is 21002002139. The reversal of 21002002120 is 2120020012.

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 = 21002002097 and 21002002106.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23865472 + ... + 23866351.

It is an arithmetic number, because the mean of its divisors is an integer number (1610949060).

Almost surely, 2^21002002120 is an apocalyptic number.

21002002120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002002120 is an abundant number, since it is smaller than the sum of its proper divisors (30548367800).

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

21002002120 is a wasteful number, since it uses less digits than its factorization.

21002002120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47731845 (or 47731841 counting only the distinct ones).

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

Adding to 21002002120 its reverse (2120020012), we get a palindrome (23122022132).

The spelling of 21002002120 in words is "twenty-one billion, two million, two thousand, one hundred twenty".