21183648391 has 4 divisors (see below), whose sum is σ = 21700322784. Its totient is φ = 20666974000.

The previous prime is 21183648389. The next prime is 21183648449. The reversal of 21183648391 is 19384638112.

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 21183648391 - 2¹ = 21183648389 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 (21183648341) 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, 258337135 + ... + 258337216.

It is an arithmetic number, because the mean of its divisors is an integer number (5425080696).

Almost surely, 2^21183648391 is an apocalyptic number.

21183648391 is a deficient number, since it is larger than the sum of its proper divisors (516674393).

21183648391 is an equidigital number, since it uses as much as digits as its factorization.

21183648391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516674392.

The product of its digits is 248832, while the sum is 46.

The spelling of 21183648391 in words is "twenty-one billion, one hundred eighty-three million, six hundred forty-eight thousand, three hundred ninety-one".