21650552009 has 4 divisors (see below), whose sum is σ = 21651027216. Its totient is φ = 21650076804.

The previous prime is 21650551991. The next prime is 21650552029. The reversal of 21650552009 is 90025505612.

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 not a de Polignac number, because 21650552009 - 2⁸ = 21650551753 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21650552009.

It is not an unprimeable number, because it can be changed into a prime (21650552029) 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, 161039 + ... + 263124.

It is an arithmetic number, because the mean of its divisors is an integer number (5412756804).

Almost surely, 2^21650552009 is an apocalyptic number.

It is an amenable number.

21650552009 is a deficient number, since it is larger than the sum of its proper divisors (475207).

21650552009 is an equidigital number, since it uses as much as digits as its factorization.

21650552009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 475206.

The product of its (nonzero) digits is 27000, while the sum is 35.

The spelling of 21650552009 in words is "twenty-one billion, six hundred fifty million, five hundred fifty-two thousand, nine".