21001132109 has 4 divisors (see below), whose sum is σ = 21002679516. Its totient is φ = 20999584704.

The previous prime is 21001132049. The next prime is 21001132157. The reversal of 21001132109 is 90123110012.

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 17955196009 + 3045936100 = 133997^2 + 55190^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001132109 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 (21001132199) 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, 753164 + ... + 780549.

It is an arithmetic number, because the mean of its divisors is an integer number (5250669879).

Almost surely, 2^21001132109 is an apocalyptic number.

It is an amenable number.

21001132109 is a deficient number, since it is larger than the sum of its proper divisors (1547407).

21001132109 is a wasteful number, since it uses less digits than its factorization.

21001132109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1547406.

The product of its (nonzero) digits is 108, while the sum is 20.

The spelling of 21001132109 in words is "twenty-one billion, one million, one hundred thirty-two thousand, one hundred nine".