65998981 has 8 divisors (see below), whose sum is σ = 70288344. Its totient is φ = 61754880.

The previous prime is 65998963. The next prime is 65998997. The reversal of 65998981 is 18989956.

65998981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 13942756 + 52056225 = 3734^2 + 7215^2 .

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

It is not a de Polignac number, because 65998981 - 2⁹ = 65998469 is a prime.

It is a super-2 number, since 2×65998981² = 8711730986076722, 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 (65998921) 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, 8280 + ... + 14161.

It is an arithmetic number, because the mean of its divisors is an integer number (8786043).

Almost surely, 2^65998981 is an apocalyptic number.

It is an amenable number.

65998981 is a deficient number, since it is larger than the sum of its proper divisors (4289363).

65998981 is a wasteful number, since it uses less digits than its factorization.

65998981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22631.

The product of its digits is 1399680, while the sum is 55.

The square root of 65998981 is about 8123.9756892792. The cubic root of 65998981 is about 404.1219222416.

The spelling of 65998981 in words is "sixty-five million, nine hundred ninety-eight thousand, nine hundred eighty-one".