21012001212 has 24 divisors (see below), whose sum is σ = 49051005136. Its totient is φ = 7000714368.

The previous prime is 21012001211. The next prime is 21012001217. The reversal of 21012001212 is 21210021012.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012001211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 384043 + ... + 435330.

Almost surely, 2^21012001212 is an apocalyptic number.

It is an amenable number.

21012001212 is an abundant number, since it is smaller than the sum of its proper divisors (28039003924).

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

21012001212 is a wasteful number, since it uses less digits than its factorization.

21012001212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821517 (or 821515 counting only the distinct ones).

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

Adding to 21012001212 its reverse (21210021012), we get a palindrome (42222022224).

The spelling of 21012001212 in words is "twenty-one billion, twelve million, one thousand, two hundred twelve".