21229364209 has 3 divisors (see below), whose sum is σ = 21229509913. Its totient is φ = 21229218506.

The previous prime is 21229364197. The next prime is 21229364213. The reversal of 21229364209 is 90246392212.

The square root of 21229364209 is 145703.

It is a perfect power (a square), and thus also a powerful number.

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 is a de Polignac number, because none of the positive numbers 2^k-21229364209 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21229364249) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 72852 + ... + 218554.

Almost surely, 2^21229364209 is an apocalyptic number.

21229364209 is the 145703-rd square number.

21229364209 is the 72852-nd centered octagonal number.

It is an amenable number.

21229364209 is a deficient number, since it is larger than the sum of its proper divisors (145704).

21229364209 is an frugal number, since it uses more digits than its factorization.

21229364209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291406 (or 145703 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 40.

The spelling of 21229364209 in words is "twenty-one billion, two hundred twenty-nine million, three hundred sixty-four thousand, two hundred nine".