21147126397 has 2 divisors, whose sum is σ = 21147126398. Its totient is φ = 21147126396.

The previous prime is 21147126359. The next prime is 21147126479. The reversal of 21147126397 is 79362174112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16872451236 + 4274675161 = 129894^2 + 65381^2 .

It is a cyclic number.

It is not a de Polignac number, because 21147126397 - 2³¹ = 18999642749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21147126347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10573563198 + 10573563199.

It is an arithmetic number, because the mean of its divisors is an integer number (10573563199).

Almost surely, 2^21147126397 is an apocalyptic number.

It is an amenable number.

21147126397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21147126397 is an equidigital number, since it uses as much as digits as its factorization.

21147126397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127008, while the sum is 43.

The spelling of 21147126397 in words is "twenty-one billion, one hundred forty-seven million, one hundred twenty-six thousand, three hundred ninety-seven".