65915681 has 8 divisors (see below), whose sum is σ = 75162024. Its totient is φ = 57265920.

The previous prime is 65915657. The next prime is 65915683. The reversal of 65915681 is 18651956.

It can be written as a sum of positive squares in 4 ways, for example, as 11022400 + 54893281 = 3320^2 + 7409^2 .

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 65915681 - 2¹⁸ = 65653537 is a prime.

It is a super-2 number, since 2×65915681² = 8689754003387522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65915683) 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, 148910 + ... + 149351.

It is an arithmetic number, because the mean of its divisors is an integer number (9395253).

Almost surely, 2^65915681 is an apocalyptic number.

It is an amenable number.

65915681 is a deficient number, since it is larger than the sum of its proper divisors (9246343).

65915681 is a wasteful number, since it uses less digits than its factorization.

65915681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298291.

The product of its digits is 64800, while the sum is 41.

The square root of 65915681 is about 8118.8472703950. The cubic root of 65915681 is about 403.9518310868.

The spelling of 65915681 in words is "sixty-five million, nine hundred fifteen thousand, six hundred eighty-one".