64921815679 has 16 divisors (see below), whose sum is σ = 78060257856. Its totient is φ = 52822713600.

The previous prime is 64921815677. The next prime is 64921815683. The reversal of 64921815679 is 97651812946.

It is a cyclic number.

It is not a de Polignac number, because 64921815679 - 2¹ = 64921815677 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64921815677) 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, 3046252 + ... + 3067489.

It is an arithmetic number, because the mean of its divisors is an integer number (4878766116).

Almost surely, 2^64921815679 is an apocalyptic number.

64921815679 is a deficient number, since it is larger than the sum of its proper divisors (13138442177).

64921815679 is a wasteful number, since it uses less digits than its factorization.

64921815679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6113826.

The product of its digits is 6531840, while the sum is 58.

The spelling of 64921815679 in words is "sixty-four billion, nine hundred twenty-one million, eight hundred fifteen thousand, six hundred seventy-nine".