21288684417 has 64 divisors (see below), whose sum is σ = 38386145280. Its totient is φ = 10134720000.

The previous prime is 21288684383. The next prime is 21288684419. The reversal of 21288684417 is 71448688212.

It is a happy number.

It is not a de Polignac number, because 21288684417 - 2¹¹ = 21288682369 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21288684417.

It is not an unprimeable number, because it can be changed into a prime (21288684419) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 391917 + ... + 442917.

It is an arithmetic number, because the mean of its divisors is an integer number (599783520).

Almost surely, 2^21288684417 is an apocalyptic number.

It is an amenable number.

21288684417 is a deficient number, since it is larger than the sum of its proper divisors (17097460863).

21288684417 is a wasteful number, since it uses less digits than its factorization.

21288684417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51174.

The product of its digits is 1376256, while the sum is 51.

The spelling of 21288684417 in words is "twenty-one billion, two hundred eighty-eight million, six hundred eighty-four thousand, four hundred seventeen".