161999999 has 8 divisors (see below), whose sum is σ = 185330688. Its totient is φ = 138716280.

The previous prime is 161999983. The next prime is 162000001. The reversal of 161999999 is 999999161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161999999 - 2⁴ = 161999983 is a prime.

It is a Duffinian number.

161999999 is a modest number, since divided by 99999 gives 1619 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161999969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4007 + ... + 18440.

It is an arithmetic number, because the mean of its divisors is an integer number (23166336).

Almost surely, 2^161999999 is an apocalyptic number.

161999999 is a deficient number, since it is larger than the sum of its proper divisors (23330689).

161999999 is a wasteful number, since it uses less digits than its factorization.

161999999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23485.

The product of its digits is 3188646, while the sum is 62.

The square root of 161999999 is about 12727.9220220741. The cubic root of 161999999 is about 545.1361767280.

The spelling of 161999999 in words is "one hundred sixty-one million, nine hundred ninety-nine thousand, nine hundred ninety-nine".