1321265188369 has 9 divisors (see below), whose sum is σ = 1536991313787. Its totient is φ = 1132506121824.

The previous prime is 1321265188361. The next prime is 1321265188433. The reversal of 1321265188369 is 9638815621231.

The square root of 1321265188369 is 1149463.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 177819925969 + 1143445262400 = 421687^2 + 1069320^2 .

It is not a de Polignac number, because 1321265188369 - 2³ = 1321265188361 is a prime.

It is a super-2 number, since 2×1321265188369² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1321265188361) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 7964137 + ... + 8128345.

It is an arithmetic number, because the mean of its divisors is an integer number (170776812643).

Almost surely, 2^{1321265188369} is an apocalyptic number.

1321265188369 is the 1149463-rd square number.

1321265188369 is the 574732-nd centered octagonal number.

It is an amenable number.

1321265188369 is a deficient number, since it is larger than the sum of its proper divisors (215726125418).

1321265188369 is an frugal number, since it uses more digits than its factorization.

1321265188369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328432 (or 164216 counting only the distinct ones).

The product of its digits is 3732480, while the sum is 55.

The spelling of 1321265188369 in words is "one trillion, three hundred twenty-one billion, two hundred sixty-five million, one hundred eighty-eight thousand, three hundred sixty-nine".