21730555909 has 4 divisors (see below), whose sum is σ = 21731068480. Its totient is φ = 21730043340.

The previous prime is 21730555907. The next prime is 21730555933. The reversal of 21730555909 is 90955503712.

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 21730555909 - 2¹ = 21730555907 is a prime.

It is a super-2 number, since 2×21730555909² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730555901) 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, 186327 + ... + 279604.

It is an arithmetic number, because the mean of its divisors is an integer number (5432767120).

Almost surely, 2^21730555909 is an apocalyptic number.

It is an amenable number.

21730555909 is a deficient number, since it is larger than the sum of its proper divisors (512571).

21730555909 is an equidigital number, since it uses as much as digits as its factorization.

21730555909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512570.

The product of its (nonzero) digits is 425250, while the sum is 46.

The spelling of 21730555909 in words is "twenty-one billion, seven hundred thirty million, five hundred fifty-five thousand, nine hundred nine".