1664606027881 has 2 divisors, whose sum is σ = 1664606027882. Its totient is φ = 1664606027880.

The previous prime is 1664606027879. The next prime is 1664606027893. The reversal of 1664606027881 is 1887206064661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 990661902400 + 673944125481 = 995320^2 + 820941^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664606027881 - 2¹ = 1664606027879 is a prime.

It is a super-2 number, since 2×1664606027881² (a number of 25 digits) contains 22 as substring.

Together with 1664606027879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1664606027281) 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, 832303013940 + 832303013941.

It is an arithmetic number, because the mean of its divisors is an integer number (832303013941).

Almost surely, 2^{1664606027881} is an apocalyptic number.

It is an amenable number.

1664606027881 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664606027881 is an equidigital number, since it uses as much as digits as its factorization.

1664606027881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4644864, while the sum is 55.

The spelling of 1664606027881 in words is "one trillion, six hundred sixty-four billion, six hundred six million, twenty-seven thousand, eight hundred eighty-one".