1601645 has 4 divisors (see below), whose sum is σ = 1921980.
Its totient is φ = 1281312.
The previous prime is 1601629. The next prime is 1601647. The reversal of 1601645 is 5461061.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5461061 = 509 ⋅10729.
It can be written as a sum of positive squares in 2 ways, for example, as 958441 + 643204 = 979^2 + 802^2
It is a cyclic number.
It is not a de Polignac number, because 1601645 - 24 = 1601629 is a prime.
It is a super-3 number, since 3×16016453 = 12325939780114233375, which contains 333 as substring.
It is a self number, because there is not a number n which added to its sum of digits gives 1601645.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (1601647) 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, 160160 + ... + 160169.
It is an arithmetic number, because the mean of its divisors is an integer number (480495).
21601645 is an apocalyptic number.
It is an amenable number.
1601645 is a deficient number, since it is larger than the sum of its proper divisors (320335).
1601645 is an equidigital number, since it uses as much as digits as its factorization.
1601645 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 320334.
The product of its (nonzero) digits is 720, while the sum is 23.
The square root of 1601645 is about 1265.5611403642.
The cubic root of 1601645 is about 117.0007792093.
Note that the first 3 decimals are identical.
It can be divided in two parts, 16016 and 45, that added together give a palindrome (16061).
The spelling of 1601645 in words is "one million, six hundred one thousand, six hundred forty-five".