15666631 has 2 divisors, whose sum is σ = 15666632. Its totient is φ = 15666630.

The previous prime is 15666613. The next prime is 15666661. The reversal of 15666631 is 13666651.

Together with previous prime (15666613) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 15666631 - 2¹³ = 15658439 is a prime.

It is a super-2 number, since 2×15666631² = 490886653780322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15666661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7833315 + 7833316.

It is an arithmetic number, because the mean of its divisors is an integer number (7833316).

Almost surely, 2^15666631 is an apocalyptic number.

15666631 is a deficient number, since it is larger than the sum of its proper divisors (1).

15666631 is an equidigital number, since it uses as much as digits as its factorization.

15666631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 34.

The square root of 15666631 is about 3958.1095234973. The cubic root of 15666631 is about 250.2218350985.

The spelling of 15666631 in words is "fifteen million, six hundred sixty-six thousand, six hundred thirty-one".