21209733809 has 8 divisors (see below), whose sum is σ = 23139697152. Its totient is φ = 19280071440.

The previous prime is 21209733773. The next prime is 21209733833. The reversal of 21209733809 is 90833790212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21209733809 - 2¹² = 21209729713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21209733809.

It is not an unprimeable number, because it can be changed into a prime (21209733899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87407 + ... + 223739.

It is an arithmetic number, because the mean of its divisors is an integer number (2892462144).

Almost surely, 2^21209733809 is an apocalyptic number.

It is an amenable number.

21209733809 is a deficient number, since it is larger than the sum of its proper divisors (1929963343).

21209733809 is a wasteful number, since it uses less digits than its factorization.

21209733809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150487.

The product of its (nonzero) digits is 163296, while the sum is 44.

The spelling of 21209733809 in words is "twenty-one billion, two hundred nine million, seven hundred thirty-three thousand, eight hundred nine".