15666397 has 2 divisors, whose sum is σ = 15666398. Its totient is φ = 15666396.

The previous prime is 15666379. The next prime is 15666451. The reversal of 15666397 is 79366651.

Together with previous prime (15666379) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15570916 + 95481 = 3946^2 + 309^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15666397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15666097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7833198 + 7833199.

It is an arithmetic number, because the mean of its divisors is an integer number (7833199).

Almost surely, 2^15666397 is an apocalyptic number.

It is an amenable number.

15666397 is a deficient number, since it is larger than the sum of its proper divisors (1).

15666397 is an equidigital number, since it uses as much as digits as its factorization.

15666397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 204120, while the sum is 43.

The square root of 15666397 is about 3958.0799638208. The cubic root of 15666397 is about 250.2205893042.

The spelling of 15666397 in words is "fifteen million, six hundred sixty-six thousand, three hundred ninety-seven".