11321716781 has 4 divisors (see below), whose sum is σ = 11322189564. Its totient is φ = 11321244000.

The previous prime is 11321716723. The next prime is 11321716787. The reversal of 11321716781 is 18761712311.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18761712311 = 6661 ⋅2816651.

It can be written as a sum of positive squares in 2 ways, for example, as 8875524100 + 2446192681 = 94210^2 + 49459^2 .

It is a cyclic number.

It is not a de Polignac number, because 11321716781 - 2⁶ = 11321716717 is a prime.

It is a super-2 number, since 2×11321716781² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11321716787) 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, 198440 + ... + 249041.

It is an arithmetic number, because the mean of its divisors is an integer number (2830547391).

Almost surely, 2^11321716781 is an apocalyptic number.

It is an amenable number.

11321716781 is a deficient number, since it is larger than the sum of its proper divisors (472783).

11321716781 is an equidigital number, since it uses as much as digits as its factorization.

11321716781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 472782.

The product of its digits is 14112, while the sum is 38.

The spelling of 11321716781 in words is "eleven billion, three hundred twenty-one million, seven hundred sixteen thousand, seven hundred eighty-one".