21670020172017 has 18 divisors (see below), whose sum is σ = 36411530493858. Its totient is φ = 12382868669472.

The previous prime is 21670020171983. The next prime is 21670020172103. The reversal of 21670020172017 is 71027102007612.

It can be written as a sum of positive squares in only one way, i.e., 19153612202256 + 2516407969761 = 4376484^2 + 1586319^2 .

It is not a de Polignac number, because 21670020172017 - 2¹⁹ = 21670019647729 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21670020172217) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 24569183428 + ... + 24569184309.

Almost surely, 2^{21670020172017} is an apocalyptic number.

It is an amenable number.

21670020172017 is a deficient number, since it is larger than the sum of its proper divisors (14741510321841).

21670020172017 is a wasteful number, since it uses less digits than its factorization.

21670020172017 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49138367757 (or 49138367747 counting only the distinct ones).

The product of its (nonzero) digits is 16464, while the sum is 36.

Adding to 21670020172017 its reverse (71027102007612), we get a palindrome (92697122179629).

The spelling of 21670020172017 in words is "twenty-one trillion, six hundred seventy billion, twenty million, one hundred seventy-two thousand, seventeen".