11661781 has 8 divisors (see below), whose sum is σ = 11965824. Its totient is φ = 11360160.

The previous prime is 11661773. The next prime is 11661827. The reversal of 11661781 is 18716611.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 11661781 - 2³ = 11661773 is a prime.

It is a super-2 number, since 2×11661781² = 271994272183922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11661701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12766 + ... + 13648.

It is an arithmetic number, because the mean of its divisors is an integer number (1495728).

Almost surely, 2^11661781 is an apocalyptic number.

It is an amenable number.

11661781 is a deficient number, since it is larger than the sum of its proper divisors (304043).

11661781 is an equidigital number, since it uses as much as digits as its factorization.

11661781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1211.

The product of its digits is 2016, while the sum is 31.

The square root of 11661781 is about 3414.9349920606. The cubic root of 11661781 is about 226.7714065628.

The spelling of 11661781 in words is "eleven million, six hundred sixty-one thousand, seven hundred eighty-one".