63665 has 16 divisors (see below), whose sum is σ = 93312. Its totient is φ = 40704.

The previous prime is 63659. The next prime is 63667. The reversal of 63665 is 56636.

63665 = 53² + 54² + ... + 69².

It is a cyclic number.

It is not a de Polignac number, because 63665 - 2⁴ = 63649 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 63665.

It is not an unprimeable number, because it can be changed into a prime (63667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 542 + ... + 648.

It is an arithmetic number, because the mean of its divisors is an integer number (5832).

2⁶³⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

63665 is a deficient number, since it is larger than the sum of its proper divisors (29647).

63665 is a wasteful number, since it uses less digits than its factorization.

With its successor (63666) it forms a Ruth-Aaron pair, since the sum of their distinct prime factors is the same (136).

63665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136.

The product of its digits is 3240, while the sum is 26.

The square root of 63665 is about 252.3192422309. The cubic root of 63665 is about 39.9300862061.

Multiplying 63665 by its sum of digits (26), we get a triangular number (1655290 = T₁₈₁₉).

The spelling of 63665 in words is "sixty-three thousand, six hundred sixty-five".