1256172149 has 12 divisors (see below), whose sum is σ = 1327793100. Its totient is φ = 1186989888.

The previous prime is 1256172139. The next prime is 1256172217. The reversal of 1256172149 is 9412716521.

It can be written as a sum of positive squares in 2 ways, for example, as 1063933924 + 192238225 = 32618^2 + 13865^2 .

It is not a de Polignac number, because 1256172149 - 2²⁸ = 987736693 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256172119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 54257 + ... + 73865.

It is an arithmetic number, because the mean of its divisors is an integer number (110649425).

Almost surely, 2^1256172149 is an apocalyptic number.

It is an amenable number.

1256172149 is a deficient number, since it is larger than the sum of its proper divisors (71620951).

1256172149 is an equidigital number, since it uses as much as digits as its factorization.

1256172149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19732 (or 19685 counting only the distinct ones).

The product of its digits is 30240, while the sum is 38.

The square root of 1256172149 is about 35442.5189426485. The cubic root of 1256172149 is about 1078.9874337269.

The spelling of 1256172149 in words is "one billion, two hundred fifty-six million, one hundred seventy-two thousand, one hundred forty-nine".