21001212000 has 144 divisors (see below), whose sum is σ = 74533429152. Its totient is φ = 5600313600.

The previous prime is 21001211977. The next prime is 21001212007. The reversal of 21001212000 is 21210012.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001212007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 255684 + ... + 327683.

It is an arithmetic number, because the mean of its divisors is an integer number (517593258).

Almost surely, 2^21001212000 is an apocalyptic number.

21001212000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001212000 is an abundant number, since it is smaller than the sum of its proper divisors (53532217152).

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

21001212000 is a wasteful number, since it uses less digits than its factorization.

21001212000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583398 (or 583377 counting only the distinct ones).

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

Adding to 21001212000 its reverse (21210012), we get a palindrome (21022422012).

The spelling of 21001212000 in words is "twenty-one billion, one million, two hundred twelve thousand".