2157565 has 4 divisors (see below), whose sum is σ = 2589084. Its totient is φ = 1726048.

The previous prime is 2157563. The next prime is 2157587. The reversal of 2157565 is 5657512.

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 674041 + 1483524 = 821^2 + 1218^2 .

It is a cyclic number.

It is not a de Polignac number, because 2157565 - 2¹ = 2157563 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157563) 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, 215752 + ... + 215761.

It is an arithmetic number, because the mean of its divisors is an integer number (647271).

2^2157565 is an apocalyptic number.

It is an amenable number.

2157565 is a deficient number, since it is larger than the sum of its proper divisors (431519).

2157565 is an equidigital number, since it uses as much as digits as its factorization.

2157565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431518.

The product of its digits is 10500, while the sum is 31.

The square root of 2157565 is about 1468.8652082475. The cubic root of 2157565 is about 129.2174886147.

The spelling of 2157565 in words is "two million, one hundred fifty-seven thousand, five hundred sixty-five".