65971639 has 4 divisors (see below), whose sum is σ = 65993440. Its totient is φ = 65949840.

The previous prime is 65971601. The next prime is 65971693. The reversal of 65971639 is 93617956.

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 65971639 - 2⁷ = 65971511 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65971739) 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, 5454 + ... + 12715.

It is an arithmetic number, because the mean of its divisors is an integer number (16498360).

Almost surely, 2^65971639 is an apocalyptic number.

65971639 is a deficient number, since it is larger than the sum of its proper divisors (21801).

65971639 is a wasteful number, since it uses less digits than its factorization.

65971639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21800.

The product of its digits is 306180, while the sum is 46.

The square root of 65971639 is about 8122.2927181923. The cubic root of 65971639 is about 404.0661081081.

The spelling of 65971639 in words is "sixty-five million, nine hundred seventy-one thousand, six hundred thirty-nine".