2161645 has 8 divisors (see below), whose sum is σ = 2621304. Its totient is φ = 1711104.

The previous prime is 2161639. The next prime is 2161697. The reversal of 2161645 is 5461612.

It can be written as a sum of positive squares in 4 ways, for example, as 328329 + 1833316 = 573^2 + 1354^2 .

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 2161645 - 2³ = 2161637 is a prime.

It is a super-3 number, since 3×2161645³ = 30302214826480233375, which contains 333 as substring.

It is a Duffinian number.

It is a congruent 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, 1744 + ... + 2713.

It is an arithmetic number, because the mean of its divisors is an integer number (327663).

2^2161645 is an apocalyptic number.

It is an amenable number.

2161645 is a deficient number, since it is larger than the sum of its proper divisors (459659).

2161645 is an equidigital number, since it uses as much as digits as its factorization.

2161645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4559.

The product of its digits is 1440, while the sum is 25.

The square root of 2161645 is about 1470.2533795234. The cubic root of 2161645 is about 129.2988883071.

The spelling of 2161645 in words is "two million, one hundred sixty-one thousand, six hundred forty-five".