161778667 has 2 divisors, whose sum is σ = 161778668. Its totient is φ = 161778666.

The previous prime is 161778611. The next prime is 161778671. The reversal of 161778667 is 766877161.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161778667 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161778667.

It is not a weakly prime, because it can be changed into another prime (161775667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80889333 + 80889334.

It is an arithmetic number, because the mean of its divisors is an integer number (80889334).

Almost surely, 2^161778667 is an apocalyptic number.

161778667 is a deficient number, since it is larger than the sum of its proper divisors (1).

161778667 is an equidigital number, since it uses as much as digits as its factorization.

161778667 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 592704, while the sum is 49.

The square root of 161778667 is about 12719.2243081094. The cubic root of 161778667 is about 544.8878000378.

The spelling of 161778667 in words is "one hundred sixty-one million, seven hundred seventy-eight thousand, six hundred sixty-seven".