21020001212 has 48 divisors (see below), whose sum is σ = 43525224960. Its totient is φ = 8690818752.

The previous prime is 21020001209. The next prime is 21020001227. The reversal of 21020001212 is 21210002012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21020001193 and 21020001202.

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 15 ways as a sum of consecutive naturals, for example, 1048103 + ... + 1067969.

It is an arithmetic number, because the mean of its divisors is an integer number (906775520).

Almost surely, 2^21020001212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21020001212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21762612480).

21020001212 is an abundant number, since it is smaller than the sum of its proper divisors (22505223748).

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

21020001212 is a wasteful number, since it uses less digits than its factorization.

21020001212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21210 (or 21208 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21020001212 its reverse (21210002012), we get a palindrome (42230003224).

The spelling of 21020001212 in words is "twenty-one billion, twenty million, one thousand, two hundred twelve".