21011221200 has 60 divisors (see below), whose sum is σ = 67305949088. Its totient is φ = 5602992000.

The previous prime is 21011221181. The next prime is 21011221223. The reversal of 21011221200 is 212211012.

It is a tau number, because it is divible by the number of its divisors (60).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8753476 + ... + 8755875.

Almost surely, 2^21011221200 is an apocalyptic number.

21011221200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011221200 is an abundant number, since it is smaller than the sum of its proper divisors (46294727888).

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

21011221200 is a wasteful number, since it uses less digits than its factorization.

21011221200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17509372 (or 17509361 counting only the distinct ones).

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

Adding to 21011221200 its reverse (212211012), we get a palindrome (21223432212).

The spelling of 21011221200 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, two hundred".