21273986197 has 2 divisors, whose sum is σ = 21273986198. Its totient is φ = 21273986196.

The previous prime is 21273986179. The next prime is 21273986203. The reversal of 21273986197 is 79168937212.

It is a happy number.

Together with previous prime (21273986179) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15308123076 + 5965863121 = 123726^2 + 77239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21273986197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21273986117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10636993098 + 10636993099.

It is an arithmetic number, because the mean of its divisors is an integer number (10636993099).

Almost surely, 2^21273986197 is an apocalyptic number.

It is an amenable number.

21273986197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21273986197 is an equidigital number, since it uses as much as digits as its factorization.

21273986197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2286144, while the sum is 55.

The spelling of 21273986197 in words is "twenty-one billion, two hundred seventy-three million, nine hundred eighty-six thousand, one hundred ninety-seven".