1256715645 has 8 divisors (see below), whose sum is σ = 2010745056. Its totient is φ = 670248336.

The previous prime is 1256715643. The next prime is 1256715661. The reversal of 1256715645 is 5465176521.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1256715645 - 2¹ = 1256715643 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 1256715597 and 1256715606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256715643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41890507 + ... + 41890536.

It is an arithmetic number, because the mean of its divisors is an integer number (251343132).

Almost surely, 2^1256715645 is an apocalyptic number.

1256715645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1256715645 is a deficient number, since it is larger than the sum of its proper divisors (754029411).

1256715645 is an equidigital number, since it uses as much as digits as its factorization.

1256715645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83781051.

The product of its digits is 252000, while the sum is 42.

The square root of 1256715645 is about 35450.1854014898. The cubic root of 1256715645 is about 1079.1430230174.

The spelling of 1256715645 in words is "one billion, two hundred fifty-six million, seven hundred fifteen thousand, six hundred forty-five".