161770991 has 2 divisors, whose sum is σ = 161770992. Its totient is φ = 161770990.

The previous prime is 161770969. The next prime is 161771003. The reversal of 161770991 is 199077161.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 161770991 - 2²² = 157576687 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161770291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80885495 + 80885496.

It is an arithmetic number, because the mean of its divisors is an integer number (80885496).

Almost surely, 2^161770991 is an apocalyptic number.

161770991 is a deficient number, since it is larger than the sum of its proper divisors (1).

161770991 is an equidigital number, since it uses as much as digits as its factorization.

161770991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23814, while the sum is 41.

The square root of 161770991 is about 12718.9225565690. The cubic root of 161770991 is about 544.8791820393.

The spelling of 161770991 in words is "one hundred sixty-one million, seven hundred seventy thousand, nine hundred ninety-one".