21111212100100 has 36 divisors (see below), whose sum is σ = 45811937293668. Its totient is φ = 8444372944000.

The previous prime is 21111212100031. The next prime is 21111212100107. The reversal of 21111212100100 is 100121211112.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 332128605636 + 20779083494464 = 576306^2 + 4558408^2 .

It is not an unprimeable number, because it can be changed into a prime (21111212100107) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6402210 + ... + 9121990.

It is an arithmetic number, because the mean of its divisors is an integer number (1272553813713).

Almost surely, 2^{21111212100100} is an apocalyptic number.

21111212100100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111212100100 is an abundant number, since it is smaller than the sum of its proper divisors (24700725193568).

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

21111212100100 is a wasteful number, since it uses less digits than its factorization.

21111212100100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2797416 (or 2797409 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21111212100100 its reverse (100121211112), we get a palindrome (21211333311212).

The spelling of 21111212100100 in words is "twenty-one trillion, one hundred eleven billion, two hundred twelve million, one hundred thousand, one hundred".