12565737409 has 3 divisors (see below), whose sum is σ = 12565849507. Its totient is φ = 12565625312.

The previous prime is 12565737313. The next prime is 12565737413. The reversal of 12565737409 is 90473756521.

The square root of 12565737409 is 112097.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 6617009025 + 5948728384 = 81345^2 + 77128^2 .

It is not a de Polignac number, because 12565737409 - 2¹¹ = 12565735361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12565737469) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 56049 + ... + 168145.

Almost surely, 2^12565737409 is an apocalyptic number.

12565737409 is the 112097-th square number.

12565737409 is the 56049-th centered octagonal number.

It is an amenable number.

12565737409 is a deficient number, since it is larger than the sum of its proper divisors (112098).

12565737409 is an frugal number, since it uses more digits than its factorization.

12565737409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224194 (or 112097 counting only the distinct ones).

The product of its (nonzero) digits is 1587600, while the sum is 49.

Multiplying 12565737409 by its sum of digits (49), we get a square (615721133041 = 784679²).

The spelling of 12565737409 in words is "twelve billion, five hundred sixty-five million, seven hundred thirty-seven thousand, four hundred nine".