21011221121100 has 144 divisors (see below), whose sum is σ = 69479344704000. Its totient is φ = 4802409976320.

The previous prime is 21011221120997. The next prime is 21011221121171. The reversal of 21011221121100 is 112112211012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21011221121100.

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 47 ways as a sum of consecutive naturals, for example, 72849976 + ... + 73137824.

Almost surely, 2^{21011221121100} is an apocalyptic number.

21011221121100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011221121100 is an abundant number, since it is smaller than the sum of its proper divisors (48468123582900).

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

21011221121100 is a wasteful number, since it uses less digits than its factorization.

21011221121100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322632 (or 322625 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21011221121100 its reverse (112112211012), we get a palindrome (21123333332112).

The spelling of 21011221121100 in words is "twenty-one trillion, eleven billion, two hundred twenty-one million, one hundred twenty-one thousand, one hundred".