21728267819 has 2 divisors, whose sum is σ = 21728267820. Its totient is φ = 21728267818.

The previous prime is 21728267807. The next prime is 21728267833. The reversal of 21728267819 is 91876282712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21728267819 - 2¹⁶ = 21728202283 is a prime.

It is a super-2 number, since 2×21728267819² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21728267419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10864133909 + 10864133910.

It is an arithmetic number, because the mean of its divisors is an integer number (10864133910).

Almost surely, 2^21728267819 is an apocalyptic number.

21728267819 is a deficient number, since it is larger than the sum of its proper divisors (1).

21728267819 is an equidigital number, since it uses as much as digits as its factorization.

21728267819 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 21728267819 in words is "twenty-one billion, seven hundred twenty-eight million, two hundred sixty-seven thousand, eight hundred nineteen".