2151665 has 4 divisors (see below), whose sum is σ = 2582004. Its totient is φ = 1721328.

The previous prime is 2151659. The next prime is 2151683. The reversal of 2151665 is 5661512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 323761 + 1827904 = 569^2 + 1352^2 .

It is a cyclic number.

It is not a de Polignac number, because 2151665 - 2¹⁰ = 2150641 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 215162 + ... + 215171.

It is an arithmetic number, because the mean of its divisors is an integer number (645501).

2^2151665 is an apocalyptic number.

It is an amenable number.

2151665 is a deficient number, since it is larger than the sum of its proper divisors (430339).

2151665 is an equidigital number, since it uses as much as digits as its factorization.

2151665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430338.

The product of its digits is 1800, while the sum is 26.

The square root of 2151665 is about 1466.8554802706. The cubic root of 2151665 is about 129.0995965822.

The spelling of 2151665 in words is "two million, one hundred fifty-one thousand, six hundred sixty-five".