161778671 has 2 divisors, whose sum is σ = 161778672. Its totient is φ = 161778670.

The previous prime is 161778667. The next prime is 161778713. The reversal of 161778671 is 176877161.

It is a weak prime.

It is an emirp because it is prime and its reverse (176877161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161778671 - 2² = 161778667 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161778611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80889335 + 80889336.

It is an arithmetic number, because the mean of its divisors is an integer number (80889336).

Almost surely, 2^161778671 is an apocalyptic number.

161778671 is a deficient number, since it is larger than the sum of its proper divisors (1).

161778671 is an equidigital number, since it uses as much as digits as its factorization.

161778671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 98784, while the sum is 44.

The square root of 161778671 is about 12719.2244653517. The cubic root of 161778671 is about 544.8878045286.

The spelling of 161778671 in words is "one hundred sixty-one million, seven hundred seventy-eight thousand, six hundred seventy-one".