21001200012 has 36 divisors (see below), whose sum is σ = 57169934640. Its totient is φ = 6461907552.

The previous prime is 21001200001. The next prime is 21001200041. The reversal of 21001200012 is 21000210012.

It is a tau number, because it is divible by the number of its divisors (36).

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 = 21001199967 and 21001200003.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22436712 + ... + 22437647.

It is an arithmetic number, because the mean of its divisors is an integer number (1588053740).

Almost surely, 2^21001200012 is an apocalyptic number.

It is an amenable number.

21001200012 is an abundant number, since it is smaller than the sum of its proper divisors (36168734628).

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

21001200012 is a wasteful number, since it uses less digits than its factorization.

21001200012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44874382 (or 44874377 counting only the distinct ones).

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

Adding to 21001200012 its reverse (21000210012), we get a palindrome (42001410024).

The spelling of 21001200012 in words is "twenty-one billion, one million, two hundred thousand, twelve".