1278257405 has 4 divisors (see below), whose sum is σ = 1533908892. Its totient is φ = 1022605920.

The previous prime is 1278257401. The next prime is 1278257467. The reversal of 1278257405 is 5047528721.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5047528721 = 4057 ⋅1244153.

It can be written as a sum of positive squares in 2 ways, for example, as 500237956 + 778019449 = 22366^2 + 27893^2 .

It is not a de Polignac number, because 1278257405 - 2² = 1278257401 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 (1278257401) 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, 127825736 + ... + 127825745.

It is an arithmetic number, because the mean of its divisors is an integer number (383477223).

Almost surely, 2^1278257405 is an apocalyptic number.

It is an amenable number.

1278257405 is a deficient number, since it is larger than the sum of its proper divisors (255651487).

1278257405 is an equidigital number, since it uses as much as digits as its factorization.

1278257405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255651486.

The product of its (nonzero) digits is 156800, while the sum is 41.

The square root of 1278257405 is about 35752.7258401370. The cubic root of 1278257405 is about 1085.2741009371.

The spelling of 1278257405 in words is "one billion, two hundred seventy-eight million, two hundred fifty-seven thousand, four hundred five".