21121221110100 has 36 divisors (see below), whose sum is σ = 61110733079424. Its totient is φ = 5632325629280.

The previous prime is 21121221110069. The next prime is 21121221110173. The reversal of 21121221110100 is 101112212112.

It is a happy number.

It is a super-2 number, since 2×21121221110100² (a number of 27 digits) contains 22 as substring.

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 21121221110100.

It is a congruent number.

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, 35202034884 + ... + 35202035483.

Almost surely, 2^{21121221110100} is an apocalyptic number.

21121221110100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121221110100 is an abundant number, since it is smaller than the sum of its proper divisors (39989511969324).

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

21121221110100 is a wasteful number, since it uses less digits than its factorization.

21121221110100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70404070384 (or 70404070377 counting only the distinct ones).

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

Adding to 21121221110100 its reverse (101112212112), we get a palindrome (21222333322212).

The spelling of 21121221110100 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twenty-one million, one hundred ten thousand, one hundred".