21100121212109 has 8 divisors (see below), whose sum is σ = 21326895146232. Its totient is φ = 20873697510400.

The previous prime is 21100121212057. The next prime is 21100121212139. The reversal of 21100121212109 is 90121212100112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9806636718025 + 11293484494084 = 3131555^2 + 3360578^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21100121212109 - 2⁸ = 21100121211853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100121212139) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87436964 + ... + 87677949.

It is an arithmetic number, because the mean of its divisors is an integer number (2665861893279).

Almost surely, 2^{21100121212109} is an apocalyptic number.

It is an amenable number.

21100121212109 is a deficient number, since it is larger than the sum of its proper divisors (226773934123).

21100121212109 is a wasteful number, since it uses less digits than its factorization.

21100121212109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175116207.

The product of its (nonzero) digits is 144, while the sum is 23.

The spelling of 21100121212109 in words is "twenty-one trillion, one hundred billion, one hundred twenty-one million, two hundred twelve thousand, one hundred nine".