1265120553 has 4 divisors (see below), whose sum is σ = 1686827408. Its totient is φ = 843413700.

The previous prime is 1265120531. The next prime is 1265120557. The reversal of 1265120553 is 3550215621.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1265120553 - 2²⁵ = 1231566121 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1265120553.

It is not an unprimeable number, because it can be changed into a prime (1265120557) 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, 210853423 + ... + 210853428.

It is an arithmetic number, because the mean of its divisors is an integer number (421706852).

Almost surely, 2^1265120553 is an apocalyptic number.

It is an amenable number.

1265120553 is a deficient number, since it is larger than the sum of its proper divisors (421706855).

1265120553 is an equidigital number, since it uses as much as digits as its factorization.

1265120553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 421706854.

The product of its (nonzero) digits is 9000, while the sum is 30.

The square root of 1265120553 is about 35568.5331859496. The cubic root of 1265120553 is about 1081.5434473305.

The spelling of 1265120553 in words is "one billion, two hundred sixty-five million, one hundred twenty thousand, five hundred fifty-three".