21001200001200 has 180 divisors, whose sum is σ = 72881983920408. Its totient is φ = 5600167372800.

The previous prime is 21001200001189. The next prime is 21001200001219. The reversal of 21001200001200 is 210000210012.

It is a tau number, because it is divible by the number of its divisors (180).

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

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 206794435 + ... + 206895965.

Almost surely, 2^{21001200001200} is an apocalyptic number.

21001200001200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001200001200 is an abundant number, since it is smaller than the sum of its proper divisors (51880783919208).

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

21001200001200 is a wasteful number, since it uses less digits than its factorization.

21001200001200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159012 (or 158998 counting only the distinct ones).

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

Adding to 21001200001200 its reverse (210000210012), we get a palindrome (21211200211212).

The spelling of 21001200001200 in words is "twenty-one trillion, one billion, two hundred million, one thousand, two hundred".