1278466645 has 4 divisors (see below), whose sum is σ = 1534159980. Its totient is φ = 1022773312.

The previous prime is 1278466613. The next prime is 1278466667. The reversal of 1278466645 is 5466648721.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5466648721 = 353 ⋅15486257.

It can be written as a sum of positive squares in 2 ways, for example, as 984892689 + 293573956 = 31383^2 + 17134^2 .

It is a cyclic number.

It is not a de Polignac number, because 1278466645 - 2⁵ = 1278466613 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent 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, 127846660 + ... + 127846669.

It is an arithmetic number, because the mean of its divisors is an integer number (383539995).

Almost surely, 2^1278466645 is an apocalyptic number.

It is an amenable number.

1278466645 is a deficient number, since it is larger than the sum of its proper divisors (255693335).

1278466645 is an equidigital number, since it uses as much as digits as its factorization.

1278466645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255693334.

The product of its digits is 1935360, while the sum is 49.

The square root of 1278466645 is about 35755.6519308486. The cubic root of 1278466645 is about 1085.3333144577. Note that the first 4 decimals are identical.

The spelling of 1278466645 in words is "one billion, two hundred seventy-eight million, four hundred sixty-six thousand, six hundred forty-five".