1665426121 has 2 divisors, whose sum is σ = 1665426122. Its totient is φ = 1665426120.

The previous prime is 1665426107. The next prime is 1665426127. The reversal of 1665426121 is 1216245661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1659666121 + 5760000 = 40739^2 + 2400^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665426121 - 2⁹ = 1665425609 is a prime.

It is not a weakly prime, because it can be changed into another prime (1665426127) 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, 832713060 + 832713061.

It is an arithmetic number, because the mean of its divisors is an integer number (832713061).

Almost surely, 2^1665426121 is an apocalyptic number.

It is an amenable number.

1665426121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665426121 is an equidigital number, since it uses as much as digits as its factorization.

1665426121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 34.

The square root of 1665426121 is about 40809.6326986656. The cubic root of 1665426121 is about 1185.3368625762.

The spelling of 1665426121 in words is "one billion, six hundred sixty-five million, four hundred twenty-six thousand, one hundred twenty-one".