21197827597 has 2 divisors, whose sum is σ = 21197827598. Its totient is φ = 21197827596.

The previous prime is 21197827543. The next prime is 21197827661. The reversal of 21197827597 is 79572879112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18925780041 + 2272047556 = 137571^2 + 47666^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21197827597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21197827507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10598913798 + 10598913799.

It is an arithmetic number, because the mean of its divisors is an integer number (10598913799).

Almost surely, 2^21197827597 is an apocalyptic number.

It is an amenable number.

21197827597 is a deficient number, since it is larger than the sum of its proper divisors (1).

21197827597 is an equidigital number, since it uses as much as digits as its factorization.

21197827597 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4445280, while the sum is 58.

The spelling of 21197827597 in words is "twenty-one billion, one hundred ninety-seven million, eight hundred twenty-seven thousand, five hundred ninety-seven".