161994999 has 4 divisors (see below), whose sum is σ = 215993336. Its totient is φ = 107996664.

The previous prime is 161994971. The next prime is 161995013. The reversal of 161994999 is 999499161.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 161994999 - 2⁹ = 161994487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161994919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26999164 + ... + 26999169.

It is an arithmetic number, because the mean of its divisors is an integer number (53998334).

Almost surely, 2^161994999 is an apocalyptic number.

161994999 is a deficient number, since it is larger than the sum of its proper divisors (53998337).

161994999 is an equidigital number, since it uses as much as digits as its factorization.

161994999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53998336.

The product of its digits is 1417176, while the sum is 57.

The square root of 161994999 is about 12727.7256020076. The cubic root of 161994999 is about 545.1305682733.

The spelling of 161994999 in words is "one hundred sixty-one million, nine hundred ninety-four thousand, nine hundred ninety-nine".