21444375217 has 4 divisors (see below), whose sum is σ = 21483579376. Its totient is φ = 21405171060.

The previous prime is 21444375193. The next prime is 21444375221. The reversal of 21444375217 is 71257344412.

It is a happy number.

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 21444375217 - 2¹¹ = 21444373169 is a prime.

It is a super-2 number, since 2×21444375217² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21444375217.

It is not an unprimeable number, because it can be changed into a prime (21444375287) 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, 19601259 + ... + 19602352.

It is an arithmetic number, because the mean of its divisors is an integer number (5370894844).

Almost surely, 2^21444375217 is an apocalyptic number.

It is an amenable number.

21444375217 is a deficient number, since it is larger than the sum of its proper divisors (39204159).

21444375217 is an equidigital number, since it uses as much as digits as its factorization.

21444375217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39204158.

The product of its digits is 188160, while the sum is 40.

The spelling of 21444375217 in words is "twenty-one billion, four hundred forty-four million, three hundred seventy-five thousand, two hundred seventeen".