1945 has 4 divisors (see below), whose sum is σ = 2340. Its totient is φ = 1552.

The previous prime is 1933. The next prime is 1949. The reversal of 1945 is 5491.

1945 is an esthetic number in base 15, because in such base its adjacent digits differ by 1.

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 576 + 1369 = 24^2 + 37^2 .

It is a cyclic number.

It is not a de Polignac number, because 1945 - 2⁵ = 1913 is a prime.

1945 is a lucky number.

It is a plaindrome in base 14, base 15 and base 16.

It is not an unprimeable number, because it can be changed into a prime (1949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 190 + ... + 199.

It is an arithmetic number, because the mean of its divisors is an integer number (585).

It is an amenable number.

1945 is a deficient number, since it is larger than the sum of its proper divisors (395).

1945 is an equidigital number, since it uses as much as digits as its factorization.

1945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394.

The product of its digits is 180, while the sum is 19.

The square root of 1945 is about 44.1021541424. The cubic root of 1945 is about 12.4826425754.

It can be divided in two parts, 19 and 45, that added together give a 6-th power (64 = 2⁶).

The spelling of 1945 in words is "one thousand, nine hundred forty-five".