21305331667 has 2 divisors, whose sum is σ = 21305331668. Its totient is φ = 21305331666.

The previous prime is 21305331631. The next prime is 21305331673. The reversal of 21305331667 is 76613350312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21305331667 - 2²⁷ = 21171113939 is a prime.

It is not a weakly prime, because it can be changed into another prime (21305331367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652665833 + 10652665834.

It is an arithmetic number, because the mean of its divisors is an integer number (10652665834).

Almost surely, 2^21305331667 is an apocalyptic number.

21305331667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21305331667 is an equidigital number, since it uses as much as digits as its factorization.

21305331667 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 68040, while the sum is 37.

Adding to 21305331667 its reverse (76613350312), we get a palindrome (97918681979).

The spelling of 21305331667 in words is "twenty-one billion, three hundred five million, three hundred thirty-one thousand, six hundred sixty-seven".