1261375521 has 16 divisors (see below), whose sum is σ = 1924067328. Its totient is φ = 720046800.

The previous prime is 1261375501. The next prime is 1261375559. The reversal of 1261375521 is 1255731621.

It is not a de Polignac number, because 1261375521 - 2⁶ = 1261375457 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1261375501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9495 + ... + 51116.

It is an arithmetic number, because the mean of its divisors is an integer number (120254208).

Almost surely, 2^1261375521 is an apocalyptic number.

It is an amenable number.

1261375521 is a deficient number, since it is larger than the sum of its proper divisors (662691807).

1261375521 is an equidigital number, since it uses as much as digits as its factorization.

1261375521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61612.

The product of its digits is 12600, while the sum is 33.

The square root of 1261375521 is about 35515.8488706099. The cubic root of 1261375521 is about 1080.4751912663.

The spelling of 1261375521 in words is "one billion, two hundred sixty-one million, three hundred seventy-five thousand, five hundred twenty-one".