1261143561 has 8 divisors (see below), whose sum is σ = 1739508480. Its totient is φ = 811770512.

The previous prime is 1261143553. The next prime is 1261143593. The reversal of 1261143561 is 1653411621.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1261143561 - 2³ = 1261143553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1261143511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7247865 + ... + 7248038.

It is an arithmetic number, because the mean of its divisors is an integer number (217438560).

Almost surely, 2^1261143561 is an apocalyptic number.

It is an amenable number.

1261143561 is a deficient number, since it is larger than the sum of its proper divisors (478364919).

1261143561 is a wasteful number, since it uses less digits than its factorization.

1261143561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14495935.

The product of its digits is 4320, while the sum is 30.

The square root of 1261143561 is about 35512.5831361223. The cubic root of 1261143561 is about 1080.4089560636.

The spelling of 1261143561 in words is "one billion, two hundred sixty-one million, one hundred forty-three thousand, five hundred sixty-one".