21668383887 has 4 divisors (see below), whose sum is σ = 28891178520. Its totient is φ = 14445589256.

The previous prime is 21668383873. The next prime is 21668383901. The reversal of 21668383887 is 78838386612.

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

It is an interprime number because it is at equal distance from previous prime (21668383873) and next prime (21668383901).

It is a cyclic number.

It is not a de Polignac number, because 21668383887 - 2⁶ = 21668383823 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21668383887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21668381887) 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, 3611397312 + ... + 3611397317.

It is an arithmetic number, because the mean of its divisors is an integer number (7222794630).

Almost surely, 2^21668383887 is an apocalyptic number.

21668383887 is a deficient number, since it is larger than the sum of its proper divisors (7222794633).

21668383887 is an equidigital number, since it uses as much as digits as its factorization.

21668383887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7222794632.

The product of its digits is 18579456, while the sum is 60.

The spelling of 21668383887 in words is "twenty-one billion, six hundred sixty-eight million, three hundred eighty-three thousand, eight hundred eighty-seven".