1205172551563 has 4 divisors (see below), whose sum is σ = 1233199820248. Its totient is φ = 1177145282880.

The previous prime is 1205172551549. The next prime is 1205172551581. The reversal of 1205172551563 is 3651552715021.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1205172551563 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 28027268641 = 1205172551563 / (1 + 2 + 0 + 5 + 1 + 7 + 2 + 5 + 5 + 1 + 5 + 6 + 3).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1205172581563) 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, 14013634278 + ... + 14013634363.

It is an arithmetic number, because the mean of its divisors is an integer number (308299955062).

Almost surely, 2^{1205172551563} is an apocalyptic number.

1205172551563 is a deficient number, since it is larger than the sum of its proper divisors (28027268685).

1205172551563 is an equidigital number, since it uses as much as digits as its factorization.

1205172551563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28027268684.

The product of its (nonzero) digits is 315000, while the sum is 43.

The spelling of 1205172551563 in words is "one trillion, two hundred five billion, one hundred seventy-two million, five hundred fifty-one thousand, five hundred sixty-three".