1666623481 has 2 divisors, whose sum is σ = 1666623482. Its totient is φ = 1666623480.

The previous prime is 1666623479. The next prime is 1666623659. The reversal of 1666623481 is 1843266661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 958212025 + 708411456 = 30955^2 + 26616^2 .

It is an emirp because it is prime and its reverse (1843266661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666623481 - 2¹ = 1666623479 is a prime.

It is a super-2 number, since 2×1666623481² = 5555267654841114722, which contains 22 as substring.

Together with 1666623479, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1666623461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833311740 + 833311741.

It is an arithmetic number, because the mean of its divisors is an integer number (833311741).

Almost surely, 2^1666623481 is an apocalyptic number.

It is an amenable number.

1666623481 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666623481 is an equidigital number, since it uses as much as digits as its factorization.

1666623481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 248832, while the sum is 43.

The square root of 1666623481 is about 40824.3001287224. The cubic root of 1666623481 is about 1185.6208609543.

The spelling of 1666623481 in words is "one billion, six hundred sixty-six million, six hundred twenty-three thousand, four hundred eighty-one".