1261917129 has 32 divisors (see below), whose sum is σ = 1951349760. Its totient is φ = 717336000.

The previous prime is 1261917119. The next prime is 1261917131. The reversal of 1261917129 is 9217191621.

It is not a de Polignac number, because 1261917129 - 2⁴ = 1261917113 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1261917109) 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 31 ways as a sum of consecutive naturals, for example, 53364 + ... + 73290.

It is an arithmetic number, because the mean of its divisors is an integer number (60979680).

Almost surely, 2^1261917129 is an apocalyptic number.

1261917129 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1261917129 is a deficient number, since it is larger than the sum of its proper divisors (689432631).

1261917129 is a wasteful number, since it uses less digits than its factorization.

1261917129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20061.

The product of its digits is 13608, while the sum is 39.

The square root of 1261917129 is about 35523.4729298812. The cubic root of 1261917129 is about 1080.6298135446.

The spelling of 1261917129 in words is "one billion, two hundred sixty-one million, nine hundred seventeen thousand, one hundred twenty-nine".