161778611 has 2 divisors, whose sum is σ = 161778612. Its totient is φ = 161778610.

The previous prime is 161778557. The next prime is 161778667. The reversal of 161778611 is 116877161.

161778611 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 161778611 - 2²⁶ = 94669747 is a prime.

It is not a weakly prime, because it can be changed into another prime (161778671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80889305 + 80889306.

It is an arithmetic number, because the mean of its divisors is an integer number (80889306).

Almost surely, 2^161778611 is an apocalyptic number.

161778611 is a deficient number, since it is larger than the sum of its proper divisors (1).

161778611 is an equidigital number, since it uses as much as digits as its factorization.

161778611 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 38.

The square root of 161778611 is about 12719.2221067171. Note that the first 3 decimals coincide. The cubic root of 161778611 is about 544.8877371665.

The spelling of 161778611 in words is "one hundred sixty-one million, seven hundred seventy-eight thousand, six hundred eleven".