161640 has 48 divisors (see below), whose sum is σ = 526500. Its totient is φ = 43008.

The previous prime is 161639. The next prime is 161641. The reversal of 161640 is 46161.

It is an interprime number because it is at equal distance from previous prime (161639) and next prime (161641).

It can be written as a sum of positive squares in 2 ways, for example, as 161604 + 36 = 402^2 + 6^2 .

It is a super-2 number, since 2×161640² = 52254979200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 136 + ... + 584.

2¹⁶¹⁶⁴⁰ is an apocalyptic number.

161640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (263250).

161640 is an abundant number, since it is smaller than the sum of its proper divisors (364860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161640 is a wasteful number, since it uses less digits than its factorization.

161640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 466 (or 459 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 161640 is about 402.0447736260. The cubic root of 161640 is about 54.4732073789.

The spelling of 161640 in words is "one hundred sixty-one thousand, six hundred forty".