21020947867 has 2 divisors, whose sum is σ = 21020947868. Its totient is φ = 21020947866.

The previous prime is 21020947847. The next prime is 21020947903. The reversal of 21020947867 is 76874902012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21020947867 - 2¹¹ = 21020945819 is a prime.

It is not a weakly prime, because it can be changed into another prime (21020947847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510473933 + 10510473934.

It is an arithmetic number, because the mean of its divisors is an integer number (10510473934).

Almost surely, 2^21020947867 is an apocalyptic number.

21020947867 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020947867 is an equidigital number, since it uses as much as digits as its factorization.

21020947867 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 338688, while the sum is 46.

The spelling of 21020947867 in words is "twenty-one billion, twenty million, nine hundred forty-seven thousand, eight hundred sixty-seven".