1261155015 has 20 divisors (see below), whose sum is σ = 2260737864. Its totient is φ = 672615792.

The previous prime is 1261155011. The next prime is 1261155017. The reversal of 1261155015 is 5105511621.

It is not a de Polignac number, because 1261155015 - 2² = 1261155011 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 1261155015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261155011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1556577 + ... + 1557386.

Almost surely, 2^1261155015 is an apocalyptic number.

1261155015 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1261155015 is a deficient number, since it is larger than the sum of its proper divisors (999582849).

1261155015 is an equidigital number, since it uses as much as digits as its factorization.

1261155015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3113980 (or 3113971 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 27.

The square root of 1261155015 is about 35512.7444025381. The cubic root of 1261155015 is about 1080.4122268957.

Adding to 1261155015 its reverse (5105511621), we get a palindrome (6366666636).

The spelling of 1261155015 in words is "one billion, two hundred sixty-one million, one hundred fifty-five thousand, fifteen".