21918242867 has 4 divisors (see below), whose sum is σ = 21927002160. Its totient is φ = 21909483576.

The previous prime is 21918242839. The next prime is 21918242881. The reversal of 21918242867 is 76824281912.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21918242867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21918242807) 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, 4375892 + ... + 4380897.

It is an arithmetic number, because the mean of its divisors is an integer number (5481750540).

Almost surely, 2^21918242867 is an apocalyptic number.

21918242867 is a deficient number, since it is larger than the sum of its proper divisors (8759293).

21918242867 is an equidigital number, since it uses as much as digits as its factorization.

21918242867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8759292.

The product of its digits is 774144, while the sum is 50.

The spelling of 21918242867 in words is "twenty-one billion, nine hundred eighteen million, two hundred forty-two thousand, eight hundred sixty-seven".