21100120101 has 12 divisors (see below), whose sum is σ = 30479260812. Its totient is φ = 14066142336.

The previous prime is 21100120099. The next prime is 21100120127. The reversal of 21100120101 is 10102100112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19663331076 + 1436789025 = 140226^2 + 37905^2 .

It is not a de Polignac number, because 21100120101 - 2¹ = 21100120099 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100120001) 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, 296355 + ... + 360591.

It is an arithmetic number, because the mean of its divisors is an integer number (2539938401).

Almost surely, 2^21100120101 is an apocalyptic number.

It is an amenable number.

21100120101 is a deficient number, since it is larger than the sum of its proper divisors (9379140711).

21100120101 is a wasteful number, since it uses less digits than its factorization.

21100120101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100740 (or 100737 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21100120101 its reverse (10102100112), we get a palindrome (31202220213).

The spelling of 21100120101 in words is "twenty-one billion, one hundred million, one hundred twenty thousand, one hundred one".