21220012109 has 4 divisors (see below), whose sum is σ = 21222151104. Its totient is φ = 21217873116.

The previous prime is 21220012097. The next prime is 21220012127. The reversal of 21220012109 is 90121002212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21220012109 is a prime.

It is a super-2 number, since 2×21220012109² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220012139) 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, 1054547 + ... + 1074480.

It is an arithmetic number, because the mean of its divisors is an integer number (5305537776).

Almost surely, 2^21220012109 is an apocalyptic number.

It is an amenable number.

21220012109 is a deficient number, since it is larger than the sum of its proper divisors (2138995).

21220012109 is an equidigital number, since it uses as much as digits as its factorization.

21220012109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2138994.

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

The spelling of 21220012109 in words is "twenty-one billion, two hundred twenty million, twelve thousand, one hundred nine".