161038991 has 2 divisors, whose sum is σ = 161038992. Its totient is φ = 161038990.

The previous prime is 161038957. The next prime is 161038993. The reversal of 161038991 is 199830161.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 161038991 - 2¹⁴ = 161022607 is a prime.

It is a Sophie Germain prime.

Together with 161038993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161038993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80519495 + 80519496.

It is an arithmetic number, because the mean of its divisors is an integer number (80519496).

Almost surely, 2^161038991 is an apocalyptic number.

161038991 is a deficient number, since it is larger than the sum of its proper divisors (1).

161038991 is an equidigital number, since it uses as much as digits as its factorization.

161038991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 161038991 is about 12690.1139080782. The cubic root of 161038991 is about 544.0560953094.

The spelling of 161038991 in words is "one hundred sixty-one million, thirty-eight thousand, nine hundred ninety-one".