21568157189 has 2 divisors, whose sum is σ = 21568157190. Its totient is φ = 21568157188.

The previous prime is 21568157183. The next prime is 21568157201. The reversal of 21568157189 is 98175186512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13448345089 + 8119812100 = 115967^2 + 90110^2 .

It is a cyclic number.

It is not a de Polignac number, because 21568157189 - 2⁸ = 21568156933 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21568157189.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21568157183) 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, 10784078594 + 10784078595.

It is an arithmetic number, because the mean of its divisors is an integer number (10784078595).

Almost surely, 2^21568157189 is an apocalyptic number.

It is an amenable number.

21568157189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21568157189 is an equidigital number, since it uses as much as digits as its factorization.

21568157189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1209600, while the sum is 53.

The spelling of 21568157189 in words is "twenty-one billion, five hundred sixty-eight million, one hundred fifty-seven thousand, one hundred eighty-nine".