161266786181 has 4 divisors (see below), whose sum is σ = 164000121600. Its totient is φ = 158533450764.

The previous prime is 161266786151. The next prime is 161266786201. The reversal of 161266786181 is 181687662161.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 181687662161 = 7817 ⋅23242633.

It is a cyclic number.

It is not a de Polignac number, because 161266786181 - 2¹⁸ = 161266524037 is a prime.

It is a super-2 number, since 2×161266786181² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161266786151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1366667621 + ... + 1366667738.

It is an arithmetic number, because the mean of its divisors is an integer number (41000030400).

Almost surely, 2^161266786181 is an apocalyptic number.

It is an amenable number.

161266786181 is a deficient number, since it is larger than the sum of its proper divisors (2733335419).

161266786181 is an equidigital number, since it uses as much as digits as its factorization.

161266786181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2733335418.

The product of its digits is 1161216, while the sum is 53.

The spelling of 161266786181 in words is "one hundred sixty-one billion, two hundred sixty-six million, seven hundred eighty-six thousand, one hundred eighty-one".