65678521639 has 4 divisors (see below), whose sum is σ = 65758326256. Its totient is φ = 65598717024.

The previous prime is 65678521621. The next prime is 65678521669. The reversal of 65678521639 is 93612587656.

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 65678521639 - 2¹³ = 65678513447 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 (65678521669) 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, 39901074 + ... + 39902719.

It is an arithmetic number, because the mean of its divisors is an integer number (16439581564).

Almost surely, 2^65678521639 is an apocalyptic number.

65678521639 is a deficient number, since it is larger than the sum of its proper divisors (79804617).

65678521639 is an equidigital number, since it uses as much as digits as its factorization.

65678521639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79804616.

The product of its digits is 16329600, while the sum is 58.

The spelling of 65678521639 in words is "sixty-five billion, six hundred seventy-eight million, five hundred twenty-one thousand, six hundred thirty-nine".