21183994847 has 2 divisors, whose sum is σ = 21183994848. Its totient is φ = 21183994846.

The previous prime is 21183994787. The next prime is 21183994877. The reversal of 21183994847 is 74849938112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21183994847 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21183994792 and 21183994801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21183994877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10591997423 + 10591997424.

It is an arithmetic number, because the mean of its divisors is an integer number (10591997424).

Almost surely, 2^21183994847 is an apocalyptic number.

21183994847 is a deficient number, since it is larger than the sum of its proper divisors (1).

21183994847 is an equidigital number, since it uses as much as digits as its factorization.

21183994847 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3483648, while the sum is 56.

The spelling of 21183994847 in words is "twenty-one billion, one hundred eighty-three million, nine hundred ninety-four thousand, eight hundred forty-seven".