21000001212 has 18 divisors (see below), whose sum is σ = 53083336488. Its totient is φ = 7000000392.

The previous prime is 21000001201. The next prime is 21000001249. The reversal of 21000001212 is 21210000012.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21000001194 and 21000001203.

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 5 ways as a sum of consecutive naturals, for example, 291666648 + ... + 291666719.

Almost surely, 2^21000001212 is an apocalyptic number.

It is an amenable number.

21000001212 is an abundant number, since it is smaller than the sum of its proper divisors (32083335276).

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

21000001212 is a wasteful number, since it uses less digits than its factorization.

21000001212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583333377 (or 583333372 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21000001212 its reverse (21210000012), we get a palindrome (42210001224).

The spelling of 21000001212 in words is "twenty-one billion, one thousand, two hundred twelve".