161665555619 has 2 divisors, whose sum is σ = 161665555620. Its totient is φ = 161665555618.

The previous prime is 161665555559. The next prime is 161665555633. The reversal of 161665555619 is 916555566161.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 161665555619 - 2¹⁶ = 161665490083 is a prime.

It is a super-2 number, since 2×161665555619² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (161665555679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80832777809 + 80832777810.

It is an arithmetic number, because the mean of its divisors is an integer number (80832777810).

Almost surely, 2^161665555619 is an apocalyptic number.

161665555619 is a deficient number, since it is larger than the sum of its proper divisors (1).

161665555619 is an equidigital number, since it uses as much as digits as its factorization.

161665555619 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7290000, while the sum is 56.

The spelling of 161665555619 in words is "one hundred sixty-one billion, six hundred sixty-five million, five hundred fifty-five thousand, six hundred nineteen".