21888390017 has 4 divisors (see below), whose sum is σ = 23572112340. Its totient is φ = 20204667696.

The previous prime is 21888389989. The next prime is 21888390031. The reversal of 21888390017 is 71009388812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3485839681 + 18402550336 = 59041^2 + 135656^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21888390017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21888390037) 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, 841861142 + ... + 841861167.

It is an arithmetic number, because the mean of its divisors is an integer number (5893028085).

Almost surely, 2^21888390017 is an apocalyptic number.

It is an amenable number.

21888390017 is a deficient number, since it is larger than the sum of its proper divisors (1683722323).

21888390017 is a wasteful number, since it uses less digits than its factorization.

21888390017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1683722322.

The product of its (nonzero) digits is 193536, while the sum is 47.

The spelling of 21888390017 in words is "twenty-one billion, eight hundred eighty-eight million, three hundred ninety thousand, seventeen".