13537197781 has 4 divisors (see below), whose sum is σ = 13540887052. Its totient is φ = 13533508512.

The previous prime is 13537197763. The next prime is 13537197787. The reversal of 13537197781 is 18779173531.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18779173531 = 9319 ⋅2015149.

It can be written as a sum of positive squares in 2 ways, for example, as 7457876881 + 6079320900 = 86359^2 + 77970^2 .

It is a cyclic number.

It is not a de Polignac number, because 13537197781 - 2²⁷ = 13402980053 is a prime.

It is a super-2 number, since 2×13537197781² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13537197787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1839126 + ... + 1846471.

It is an arithmetic number, because the mean of its divisors is an integer number (3385221763).

Almost surely, 2^13537197781 is an apocalyptic number.

It is an amenable number.

13537197781 is a deficient number, since it is larger than the sum of its proper divisors (3689271).

13537197781 is an equidigital number, since it uses as much as digits as its factorization.

13537197781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3689270.

The product of its digits is 1111320, while the sum is 52.

The spelling of 13537197781 in words is "thirteen billion, five hundred thirty-seven million, one hundred ninety-seven thousand, seven hundred eighty-one".