12811945 has 4 divisors (see below), whose sum is σ = 15374340. Its totient is φ = 10249552.

The previous prime is 12811937. The next prime is 12811957. The reversal of 12811945 is 54911821.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54911821 = 2333 ⋅23537.

It can be written as a sum of positive squares in 2 ways, for example, as 4791721 + 8020224 = 2189^2 + 2832^2 .

It is a cyclic number.

It is not a de Polignac number, because 12811945 - 2³ = 12811937 is a prime.

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, 1281190 + ... + 1281199.

It is an arithmetic number, because the mean of its divisors is an integer number (3843585).

Almost surely, 2^12811945 is an apocalyptic number.

It is an amenable number.

12811945 is a deficient number, since it is larger than the sum of its proper divisors (2562395).

12811945 is an equidigital number, since it uses as much as digits as its factorization.

12811945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2562394.

The product of its digits is 2880, while the sum is 31.

The square root of 12811945 is about 3579.3777392167. The cubic root of 12811945 is about 233.9941618335.

It can be divided in two parts, 128119 and 45, that added together give a square (128164 = 358²).

The spelling of 12811945 in words is "twelve million, eight hundred eleven thousand, nine hundred forty-five".