161655761012491 has 2 divisors, whose sum is σ = 161655761012492. Its totient is φ = 161655761012490.

The previous prime is 161655761012443. The next prime is 161655761012563. The reversal of 161655761012491 is 194210167556161.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 161655761012491 - 2⁷ = 161655761012363 is a prime.

It is a super-2 number, since 2×161655761012491² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161655761012411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80827880506245 + 80827880506246.

It is an arithmetic number, because the mean of its divisors is an integer number (80827880506246).

Almost surely, 2^{161655761012491} is an apocalyptic number.

161655761012491 is a deficient number, since it is larger than the sum of its proper divisors (1).

161655761012491 is an equidigital number, since it uses as much as digits as its factorization.

161655761012491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2721600, while the sum is 55.

The spelling of 161655761012491 in words is "one hundred sixty-one trillion, six hundred fifty-five billion, seven hundred sixty-one million, twelve thousand, four hundred ninety-one".