21212021012 has 72 divisors (see below), whose sum is σ = 47492976384. Its totient is φ = 8212978368.

The previous prime is 21212020987. The next prime is 21212021023. The reversal of 21212021012 is 21012021212.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31193 + ... + 208319.

It is an arithmetic number, because the mean of its divisors is an integer number (659624672).

Almost surely, 2^21212021012 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 21212021012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23746488192).

21212021012 is an abundant number, since it is smaller than the sum of its proper divisors (26280955372).

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

21212021012 is a wasteful number, since it uses less digits than its factorization.

21212021012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177205 (or 177196 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21212021012 its reverse (21012021212), we get a palindrome (42224042224).

The spelling of 21212021012 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, twelve".