21447700217 has 8 divisors (see below), whose sum is σ = 21864685320. Its totient is φ = 21031171200.

The previous prime is 21447700187. The next prime is 21447700273. The reversal of 21447700217 is 71200774412.

It can be written as a sum of positive squares in 4 ways, for example, as 17435617936 + 4012082281 = 132044^2 + 63341^2 .

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 21447700217 - 2⁸ = 21447699961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21447700297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18284 + ... + 207917.

It is an arithmetic number, because the mean of its divisors is an integer number (2733085665).

Almost surely, 2^21447700217 is an apocalyptic number.

It is an amenable number.

21447700217 is a deficient number, since it is larger than the sum of its proper divisors (416985103).

21447700217 is a wasteful number, since it uses less digits than its factorization.

21447700217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228043.

The product of its (nonzero) digits is 21952, while the sum is 35.

The spelling of 21447700217 in words is "twenty-one billion, four hundred forty-seven million, seven hundred thousand, two hundred seventeen".