1666531 has 2 divisors, whose sum is σ = 1666532. Its totient is φ = 1666530.

The previous prime is 1666523. The next prime is 1666541. The reversal of 1666531 is 1356661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1666531 - 2³ = 1666523 is a prime.

It is a super-2 number, since 2×1666531² = 5554651147922, which contains 22 as substring.

1666531 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1666531.

It is not a weakly prime, because it can be changed into another prime (1666541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833265 + 833266.

It is an arithmetic number, because the mean of its divisors is an integer number (833266).

2^1666531 is an apocalyptic number.

1666531 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666531 is an equidigital number, since it uses as much as digits as its factorization.

1666531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3240, while the sum is 28.

The square root of 1666531 is about 1290.9419041924. The cubic root of 1666531 is about 118.5598930500.

It can be divided in two parts, 16665 and 31, that multiplied together give a palindrome (516615).

The spelling of 1666531 in words is "one million, six hundred sixty-six thousand, five hundred thirty-one".