21212101020 has 72 divisors (see below), whose sum is σ = 65284207632. Its totient is φ = 5142325760.

The previous prime is 21212100983. The next prime is 21212101039. The reversal of 21212101020 is 2010121212.

It is a super-3 number, since 3×21212101020³ (a number of 32 digits) contains 333 as substring.

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 = 21212100987 and 21212101005.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1453629 + ... + 1468148.

It is an arithmetic number, because the mean of its divisors is an integer number (906725106).

Almost surely, 2^21212101020 is an apocalyptic number.

21212101020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212101020 is an abundant number, since it is smaller than the sum of its proper divisors (44072106612).

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

21212101020 is a wasteful number, since it uses less digits than its factorization.

21212101020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2921811 (or 2921798 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21212101020 its reverse (2010121212), we get a palindrome (23222222232).

The spelling of 21212101020 in words is "twenty-one billion, two hundred twelve million, one hundred one thousand, twenty".