65721705 has 64 divisors (see below), whose sum is σ = 126468096. Its totient is φ = 28512000.

The previous prime is 65721683. The next prime is 65721709. The reversal of 65721705 is 50712756.

It is not a de Polignac number, because 65721705 - 2⁷ = 65721577 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (65721709) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 198390 + ... + 198720.

It is an arithmetic number, because the mean of its divisors is an integer number (1976064).

Almost surely, 2^65721705 is an apocalyptic number.

It is an amenable number.

65721705 is a deficient number, since it is larger than the sum of its proper divisors (60746391).

65721705 is a wasteful number, since it uses less digits than its factorization.

65721705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 438.

The product of its (nonzero) digits is 14700, while the sum is 33.

The square root of 65721705 is about 8106.8924379197. The cubic root of 65721705 is about 403.5551933025. Note that the first 3 decimals are identical.

The spelling of 65721705 in words is "sixty-five million, seven hundred twenty-one thousand, seven hundred five".