21001002220109 has 4 divisors (see below), whose sum is σ = 21002112404604. Its totient is φ = 20999892035616.

The previous prime is 21001002220091. The next prime is 21001002220111. The reversal of 21001002220109 is 90102220010012.

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 16126223968009 + 4874778252100 = 4015747^2 + 2207890^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001002220109 - 2²⁴ = 21000985442893 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 (21001002220129) 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, 555063872 + ... + 555101705.

It is an arithmetic number, because the mean of its divisors is an integer number (5250528101151).

Almost surely, 2^{21001002220109} is an apocalyptic number.

It is an amenable number.

21001002220109 is a deficient number, since it is larger than the sum of its proper divisors (1110184495).

21001002220109 is a wasteful number, since it uses less digits than its factorization.

21001002220109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1110184494.

The product of its (nonzero) digits is 144, while the sum is 20.

The spelling of 21001002220109 in words is "twenty-one trillion, one billion, two million, two hundred twenty thousand, one hundred nine".