21998166287 has 4 divisors (see below), whose sum is σ = 22041900720. Its totient is φ = 21954431856.

The previous prime is 21998166283. The next prime is 21998166293. The reversal of 21998166287 is 78266189912.

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

It is a cyclic number.

It is not a de Polignac number, because 21998166287 - 2² = 21998166283 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21998166283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21866462 + ... + 21867467.

It is an arithmetic number, because the mean of its divisors is an integer number (5510475180).

Almost surely, 2^21998166287 is an apocalyptic number.

21998166287 is a deficient number, since it is larger than the sum of its proper divisors (43734433).

21998166287 is an equidigital number, since it uses as much as digits as its factorization.

21998166287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43734432.

The product of its digits is 5225472, while the sum is 59.

The spelling of 21998166287 in words is "twenty-one billion, nine hundred ninety-eight million, one hundred sixty-six thousand, two hundred eighty-seven".