11781816 has 64 divisors (see below), whose sum is σ = 31726080. Its totient is φ = 3632640.

The previous prime is 11781787. The next prime is 11781827. The reversal of 11781816 is 61818711.

It is a super-2 number, since 2×11781816² = 277622376515712, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27121 + ... + 27551.

It is an arithmetic number, because the mean of its divisors is an integer number (495720).

Almost surely, 2^11781816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 11781816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15863040).

11781816 is an abundant number, since it is smaller than the sum of its proper divisors (19944264).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

11781816 is a wasteful number, since it uses less digits than its factorization.

11781816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 524 (or 520 counting only the distinct ones).

The product of its digits is 2688, while the sum is 33.

The square root of 11781816 is about 3432.4650034633. The cubic root of 11781816 is about 227.5468067762.

The spelling of 11781816 in words is "eleven million, seven hundred eighty-one thousand, eight hundred sixteen".