2156905 has 4 divisors (see below), whose sum is σ = 2588292. Its totient is φ = 1725520.

The previous prime is 2156897. The next prime is 2156939. The reversal of 2156905 is 5096512.

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 549081 + 1607824 = 741^2 + 1268^2 .

It is not a de Polignac number, because 2156905 - 2³ = 2156897 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, 215686 + ... + 215695.

It is an arithmetic number, because the mean of its divisors is an integer number (647073).

2^2156905 is an apocalyptic number.

It is an amenable number.

2156905 is a deficient number, since it is larger than the sum of its proper divisors (431387).

2156905 is an equidigital number, since it uses as much as digits as its factorization.

2156905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431386.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 2156905 is about 1468.6405278352. The cubic root of 2156905 is about 129.2043113771.

The spelling of 2156905 in words is "two million, one hundred fifty-six thousand, nine hundred five".