15666731 has 2 divisors, whose sum is σ = 15666732. Its totient is φ = 15666730.

The previous prime is 15666701. The next prime is 15666733. The reversal of 15666731 is 13766651.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 15666731 - 2¹⁰ = 15665707 is a prime.

It is a super-2 number, since 2×15666731² = 490892920452722, which contains 22 as substring.

Together with 15666733, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 15666691 and 15666700.

It is not a weakly prime, because it can be changed into another prime (15666733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7833365 + 7833366.

It is an arithmetic number, because the mean of its divisors is an integer number (7833366).

Almost surely, 2^15666731 is an apocalyptic number.

15666731 is a deficient number, since it is larger than the sum of its proper divisors (1).

15666731 is an equidigital number, since it uses as much as digits as its factorization.

15666731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 35.

The square root of 15666731 is about 3958.1221557703. The cubic root of 15666731 is about 250.2223674855. Note that the first 3 decimals are identical.

The spelling of 15666731 in words is "fifteen million, six hundred sixty-six thousand, seven hundred thirty-one".