21100111001 has 4 divisors (see below), whose sum is σ = 21104389812. Its totient is φ = 21095832192.

The previous prime is 21100110989. The next prime is 21100111009. The reversal of 21100111001 is 10011100112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12421325401 + 8678785600 = 111451^2 + 93160^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100111001 - 2²² = 21095916697 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21100111001.

It is not an unprimeable number, because it can be changed into a prime (21100111009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2132000 + ... + 2141873.

It is an arithmetic number, because the mean of its divisors is an integer number (5276097453).

Almost surely, 2^21100111001 is an apocalyptic number.

It is an amenable number.

21100111001 is a deficient number, since it is larger than the sum of its proper divisors (4278811).

21100111001 is an equidigital number, since it uses as much as digits as its factorization.

21100111001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4278810.

The product of its (nonzero) digits is 2, while the sum is 8.

Adding to 21100111001 its reverse (10011100112), we get a palindrome (31111211113).

The spelling of 21100111001 in words is "twenty-one billion, one hundred million, one hundred eleven thousand, one".