21030321209 has 4 divisors (see below), whose sum is σ = 22137180240. Its totient is φ = 19923462180.

The previous prime is 21030321199. The next prime is 21030321227. The reversal of 21030321209 is 90212303012.

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-21030321209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21030321269) 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, 553429487 + ... + 553429524.

It is an arithmetic number, because the mean of its divisors is an integer number (5534295060).

Almost surely, 2^21030321209 is an apocalyptic number.

It is an amenable number.

21030321209 is a deficient number, since it is larger than the sum of its proper divisors (1106859031).

21030321209 is a wasteful number, since it uses less digits than its factorization.

21030321209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1106859030.

The product of its (nonzero) digits is 648, while the sum is 23.

The spelling of 21030321209 in words is "twenty-one billion, thirty million, three hundred twenty-one thousand, two hundred nine".