65815 has 4 divisors (see below), whose sum is σ = 78984. Its totient is φ = 52648.

The previous prime is 65809. The next prime is 65827. The reversal of 65815 is 51856.

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

It is a cyclic number.

It is not a de Polignac number, because 65815 - 2⁷ = 65687 is a prime.

It is a super-2 number, since 2×65815² = 8663228450, which contains 22 as substring.

It is a Duffinian number.

65815 is a lucky number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 65815.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6577 + ... + 6586.

It is an arithmetic number, because the mean of its divisors is an integer number (19746).

2⁶⁵⁸¹⁵ is an apocalyptic number.

65815 is a deficient number, since it is larger than the sum of its proper divisors (13169).

65815 is a wasteful number, since it uses less digits than its factorization.

65815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13168.

The product of its digits is 1200, while the sum is 25.

The square root of 65815 is about 256.5443431456. The cubic root of 65815 is about 40.3746058105.

It can be divided in two parts, 658 and 15, that multiplied together give a triangular number (9870 = T₁₄₀).

The spelling of 65815 in words is "sixty-five thousand, eight hundred fifteen".