165890 has 16 divisors (see below), whose sum is σ = 305208. Its totient is φ = 64896.

The previous prime is 165887. The next prime is 165901. The reversal of 165890 is 98561.

165890 = T₂₈₆ + T₂₈₇ + ... + T₂₈₉.

It can be written as a sum of positive squares in 4 ways, for example, as 96721 + 69169 = 311^2 + 263^2 .

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 374 + ... + 686.

2¹⁶⁵⁸⁹⁰ is an apocalyptic number.

165890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

165890 is a deficient number, since it is larger than the sum of its proper divisors (139318).

165890 is a wasteful number, since it uses less digits than its factorization.

165890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 373.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 165890 is about 407.2959611879. The cubic root of 165890 is about 54.9465044585.

The spelling of 165890 in words is "one hundred sixty-five thousand, eight hundred ninety".