161899 has 4 divisors (see below), whose sum is σ = 170440. Its totient is φ = 153360.

The previous prime is 161881. The next prime is 161911. The reversal of 161899 is 998161.

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

It is a cyclic number.

It is not a de Polignac number, because 161899 - 2⁷ = 161771 is a prime.

It is a super-2 number, since 2×161899² = 52422572402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161839) 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, 4242 + ... + 4279.

It is an arithmetic number, because the mean of its divisors is an integer number (42610).

2¹⁶¹⁸⁹⁹ is an apocalyptic number.

161899 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

161899 is a deficient number, since it is larger than the sum of its proper divisors (8541).

161899 is an equidigital number, since it uses as much as digits as its factorization.

161899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8540.

The product of its digits is 3888, while the sum is 34.

The square root of 161899 is about 402.3667481291. The cubic root of 161899 is about 54.5022864681.

The spelling of 161899 in words is "one hundred sixty-one thousand, eight hundred ninety-nine".