21212000020 has 24 divisors (see below), whose sum is σ = 44548102368. Its totient is φ = 8484247200.

The previous prime is 21211999979. The next prime is 21212000021. The reversal of 21212000020 is 2000021212.

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 = 21211999970 and 21212000006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212000021) by changing a digit.

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, 437175 + ... + 483265.

It is an arithmetic number, because the mean of its divisors is an integer number (1856170932).

Almost surely, 2^21212000020 is an apocalyptic number.

21212000020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212000020 is an abundant number, since it is smaller than the sum of its proper divisors (23336102348).

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

21212000020 is a wasteful number, since it uses less digits than its factorization.

21212000020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69111 (or 69109 counting only the distinct ones).

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

Adding to 21212000020 its reverse (2000021212), we get a palindrome (23212021232).

The spelling of 21212000020 in words is "twenty-one billion, two hundred twelve million, twenty", and thus it is an aban number.