16605881 has 2 divisors, whose sum is σ = 16605882. Its totient is φ = 16605880.

The previous prime is 16605877. The next prime is 16605917. The reversal of 16605881 is 18850661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16605625 + 256 = 4075^2 + 16^2 .

It is an emirp because it is prime and its reverse (18850661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16605881 - 2² = 16605877 is a prime.

It is a super-2 number, since 2×16605881² = 551510567572322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (16605851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8302940 + 8302941.

It is an arithmetic number, because the mean of its divisors is an integer number (8302941).

Almost surely, 2^16605881 is an apocalyptic number.

It is an amenable number.

16605881 is a deficient number, since it is larger than the sum of its proper divisors (1).

16605881 is an equidigital number, since it uses as much as digits as its factorization.

16605881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11520, while the sum is 35.

The square root of 16605881 is about 4075.0314109219. The cubic root of 16605881 is about 255.1255616416.

The spelling of 16605881 in words is "sixteen million, six hundred five thousand, eight hundred eighty-one".