21294122009 has 4 divisors (see below), whose sum is σ = 21294426804. Its totient is φ = 21293817216.

The previous prime is 21294121999. The next prime is 21294122033. The reversal of 21294122009 is 90022149212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 18660379609 + 2633742400 = 136603^2 + 51320^2 .

It is a cyclic number.

It is not a de Polignac number, because 21294122009 - 2⁸ = 21294121753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21294122609) 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, 10289 + ... + 206625.

It is an arithmetic number, because the mean of its divisors is an integer number (5323606701).

Almost surely, 2^21294122009 is an apocalyptic number.

It is an amenable number.

21294122009 is a deficient number, since it is larger than the sum of its proper divisors (304795).

21294122009 is a wasteful number, since it uses less digits than its factorization.

21294122009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304794.

The product of its (nonzero) digits is 5184, while the sum is 32.

The spelling of 21294122009 in words is "twenty-one billion, two hundred ninety-four million, one hundred twenty-two thousand, nine".