1261005601 has 4 divisors (see below), whose sum is σ = 1261666692. Its totient is φ = 1260344512.

The previous prime is 1261005527. The next prime is 1261005611. The reversal of 1261005601 is 1065001621.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1025536576 + 235469025 = 32024^2 + 15345^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261005601 - 2⁹ = 1261005089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261005611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 327676 + ... + 331501.

It is an arithmetic number, because the mean of its divisors is an integer number (315416673).

Almost surely, 2^1261005601 is an apocalyptic number.

It is an amenable number.

1261005601 is a deficient number, since it is larger than the sum of its proper divisors (661091).

1261005601 is an equidigital number, since it uses as much as digits as its factorization.

1261005601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 661090.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 1261005601 is about 35510.6406729025. The cubic root of 1261005601 is about 1080.3695583139.

The spelling of 1261005601 in words is "one billion, two hundred sixty-one million, five thousand, six hundred one".