21002212020 has 96 divisors (see below), whose sum is σ = 62125660800. Its totient is φ = 5286587904.

The previous prime is 21002211991. The next prime is 21002212093. The reversal of 21002212020 is 2021220012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21002211987 and 21002212005.

It is a congruent number.

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 31 ways as a sum of consecutive naturals, for example, 282526 + ... + 349034.

It is an arithmetic number, because the mean of its divisors is an integer number (647142300).

Almost surely, 2^21002212020 is an apocalyptic number.

21002212020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21002212020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31062830400).

21002212020 is an abundant number, since it is smaller than the sum of its proper divisors (41123448780).

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

21002212020 is a wasteful number, since it uses less digits than its factorization.

21002212020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66817 (or 66815 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

Adding to 21002212020 its reverse (2021220012), we get a palindrome (23023432032).

The spelling of 21002212020 in words is "twenty-one billion, two million, two hundred twelve thousand, twenty".