64688891 has 4 divisors (see below), whose sum is σ = 64899912. Its totient is φ = 64477872.

The previous prime is 64688843. The next prime is 64688917. The reversal of 64688891 is 19888646.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64688891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64688801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105050 + ... + 105663.

It is an arithmetic number, because the mean of its divisors is an integer number (16224978).

Almost surely, 2^64688891 is an apocalyptic number.

64688891 is a deficient number, since it is larger than the sum of its proper divisors (211021).

64688891 is a wasteful number, since it uses less digits than its factorization.

64688891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211020.

The product of its digits is 663552, while the sum is 50.

The square root of 64688891 is about 8042.9404448871. The cubic root of 64688891 is about 401.4300707346.

The spelling of 64688891 in words is "sixty-four million, six hundred eighty-eight thousand, eight hundred ninety-one".