21005522209 has 8 divisors (see below), whose sum is σ = 24082043328. Its totient is φ = 17947934160.

The previous prime is 21005522177. The next prime is 21005522243. The reversal of 21005522209 is 90222550012.

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 21005522209 - 2⁵ = 21005522177 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21005522249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4730887 + ... + 4735324.

It is an arithmetic number, because the mean of its divisors is an integer number (3010255416).

Almost surely, 2^21005522209 is an apocalyptic number.

It is an amenable number.

21005522209 is a deficient number, since it is larger than the sum of its proper divisors (3076521119).

21005522209 is an equidigital number, since it uses as much as digits as its factorization.

21005522209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9466535.

The product of its (nonzero) digits is 3600, while the sum is 28.

The spelling of 21005522209 in words is "twenty-one billion, five million, five hundred twenty-two thousand, two hundred nine".