21721832305 has 8 divisors (see below), whose sum is σ = 26069697000. Its totient is φ = 17375133696.

The previous prime is 21721832303. The next prime is 21721832311. The reversal of 21721832305 is 50323812712.

It can be written as a sum of positive squares in 4 ways, for example, as 8514306529 + 13207525776 = 92273^2 + 114924^2 .

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 21721832305 - 2¹ = 21721832303 is a prime.

It is a super-2 number, since 2×21721832305² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21721832303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 250000 + ... + 325489.

It is an arithmetic number, because the mean of its divisors is an integer number (3258712125).

Almost surely, 2^21721832305 is an apocalyptic number.

It is an amenable number.

21721832305 is a deficient number, since it is larger than the sum of its proper divisors (4347864695).

21721832305 is an equidigital number, since it uses as much as digits as its factorization.

21721832305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583043.

The product of its (nonzero) digits is 20160, while the sum is 34.

The spelling of 21721832305 in words is "twenty-one billion, seven hundred twenty-one million, eight hundred thirty-two thousand, three hundred five".