21671816867 has 4 divisors (see below), whose sum is σ = 21882222960. Its totient is φ = 21461410776.

The previous prime is 21671816849. The next prime is 21671816911. The reversal of 21671816867 is 76861817612.

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 21671816867 - 2⁸ = 21671816611 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21671816807) 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, 105202892 + ... + 105203097.

It is an arithmetic number, because the mean of its divisors is an integer number (5470555740).

Almost surely, 2^21671816867 is an apocalyptic number.

21671816867 is a deficient number, since it is larger than the sum of its proper divisors (210406093).

21671816867 is a wasteful number, since it uses less digits than its factorization.

21671816867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210406092.

The product of its digits is 1354752, while the sum is 53.

The spelling of 21671816867 in words is "twenty-one billion, six hundred seventy-one million, eight hundred sixteen thousand, eight hundred sixty-seven".