65818981 has 4 divisors (see below), whose sum is σ = 67424364. Its totient is φ = 64213600.

The previous prime is 65818969. The next prime is 65818999. The reversal of 65818981 is 18981856.

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 5616900 + 60202081 = 2370^2 + 7759^2 .

It is a cyclic number.

It is not a de Polignac number, because 65818981 - 2⁹ = 65818469 is a prime.

It is a super-2 number, since 2×65818981² = 8664276519756722, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65818901) 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, 802630 + ... + 802711.

It is an arithmetic number, because the mean of its divisors is an integer number (16856091).

Almost surely, 2^65818981 is an apocalyptic number.

It is an amenable number.

65818981 is a deficient number, since it is larger than the sum of its proper divisors (1605383).

65818981 is a wasteful number, since it uses less digits than its factorization.

65818981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1605382.

The product of its digits is 138240, while the sum is 46.

The square root of 65818981 is about 8112.8898057351. The cubic root of 65818981 is about 403.7541985013.

The spelling of 65818981 in words is "sixty-five million, eight hundred eighteen thousand, nine hundred eighty-one".