21111212210100 has 72 divisors (see below), whose sum is σ = 61112362495968. Its totient is φ = 5626837372800.

The previous prime is 21111212210047. The next prime is 21111212210107. The reversal of 21111212210100 is 101221211112.

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 21111212210100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111212210107) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17020006 + ... + 18218205.

It is an arithmetic number, because the mean of its divisors is an integer number (848782812444).

Almost surely, 2^{21111212210100} is an apocalyptic number.

21111212210100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111212210100 is an abundant number, since it is smaller than the sum of its proper divisors (40001150285868).

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

21111212210100 is a wasteful number, since it uses less digits than its factorization.

21111212210100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35240225 (or 35240218 counting only the distinct ones).

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

Adding to 21111212210100 its reverse (101221211112), we get a palindrome (21212433421212).

The spelling of 21111212210100 in words is "twenty-one trillion, one hundred eleven billion, two hundred twelve million, two hundred ten thousand, one hundred".