16549981 has 8 divisors (see below), whose sum is σ = 19566720. Its totient is φ = 13696368.

The previous prime is 16549963. The next prime is 16549987. The reversal of 16549981 is 18994561.

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

It is not a de Polignac number, because 16549981 - 2⁷ = 16549853 is a prime.

It is a super-2 number, since 2×16549981² = 547803742200722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16549987) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 40561 + ... + 40966.

It is an arithmetic number, because the mean of its divisors is an integer number (2445840).

Almost surely, 2^16549981 is an apocalyptic number.

It is an amenable number.

16549981 is a deficient number, since it is larger than the sum of its proper divisors (3016739).

16549981 is an equidigital number, since it uses as much as digits as its factorization.

16549981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81563.

The product of its digits is 77760, while the sum is 43.

The square root of 16549981 is about 4068.1667861581. The cubic root of 16549981 is about 254.8389653522.

The spelling of 16549981 in words is "sixteen million, five hundred forty-nine thousand, nine hundred eighty-one".