91781369 has 4 divisors (see below), whose sum is σ = 92451444. Its totient is φ = 91111296.

The previous prime is 91781341. The next prime is 91781377. The reversal of 91781369 is 96318719.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18593344 + 73188025 = 4312^2 + 8555^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91781369 is a prime.

It is a super-2 number, since 2×91781369² = 16847639391028322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91781309) 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, 334832 + ... + 335105.

It is an arithmetic number, because the mean of its divisors is an integer number (23112861).

Almost surely, 2^91781369 is an apocalyptic number.

It is an amenable number.

91781369 is a deficient number, since it is larger than the sum of its proper divisors (670075).

91781369 is a wasteful number, since it uses less digits than its factorization.

91781369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670074.

The product of its digits is 81648, while the sum is 44.

The square root of 91781369 is about 9580.2593388697. The cubic root of 91781369 is about 451.0778590037.

The spelling of 91781369 in words is "ninety-one million, seven hundred eighty-one thousand, three hundred sixty-nine".