16807981 has 4 divisors (see below), whose sum is σ = 16840764. Its totient is φ = 16775200.

The previous prime is 16807957. The next prime is 16807997. The reversal of 16807981 is 18970861.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3006756 + 13801225 = 1734^2 + 3715^2 .

It is a cyclic number.

It is not a de Polignac number, because 16807981 - 2¹¹ = 16805933 is a prime.

It is a super-2 number, since 2×16807981² = 565016450592722, 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 (16805981) 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, 15610 + ... + 16651.

It is an arithmetic number, because the mean of its divisors is an integer number (4210191).

Almost surely, 2^16807981 is an apocalyptic number.

It is an amenable number.

16807981 is a deficient number, since it is larger than the sum of its proper divisors (32783).

16807981 is an equidigital number, since it uses as much as digits as its factorization.

16807981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32782.

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 16807981 is about 4099.7537730942. The cubic root of 16807981 is about 256.1563833321.

The spelling of 16807981 in words is "sixteen million, eight hundred seven thousand, nine hundred eighty-one".