17990981 has 8 divisors (see below), whose sum is σ = 19099800. Its totient is φ = 16887808.

The previous prime is 17990969. The next prime is 17990983. The reversal of 17990981 is 18909971.

It can be written as a sum of positive squares in 4 ways, for example, as 3045025 + 14945956 = 1745^2 + 3866^2 .

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 17990981 - 2¹⁴ = 17974597 is a prime.

It is a super-2 number, since 2×17990981² = 647350794684722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (17990983) 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, 6455 + ... + 8811.

It is an arithmetic number, because the mean of its divisors is an integer number (2387475).

Almost surely, 2^17990981 is an apocalyptic number.

It is an amenable number.

17990981 is a deficient number, since it is larger than the sum of its proper divisors (1108819).

17990981 is a wasteful number, since it uses less digits than its factorization.

17990981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2823.

The product of its (nonzero) digits is 40824, while the sum is 44.

The square root of 17990981 is about 4241.5776545998. The cubic root of 17990981 is about 262.0303608737.

The spelling of 17990981 in words is "seventeen million, nine hundred ninety thousand, nine hundred eighty-one".