66788905 has 4 divisors (see below), whose sum is σ = 80146692. Its totient is φ = 53431120.

The previous prime is 66788881. The next prime is 66788947. The reversal of 66788905 is 50988766.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50988766 = 2 ⋅25494383.

It can be written as a sum of positive squares in 2 ways, for example, as 46022656 + 20766249 = 6784^2 + 4557^2 .

It is not a de Polignac number, because 66788905 - 2⁵ = 66788873 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6678886 + ... + 6678895.

It is an arithmetic number, because the mean of its divisors is an integer number (20036673).

Almost surely, 2^66788905 is an apocalyptic number.

It is an amenable number.

66788905 is a deficient number, since it is larger than the sum of its proper divisors (13357787).

66788905 is a wasteful number, since it uses less digits than its factorization.

66788905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13357786.

The product of its (nonzero) digits is 725760, while the sum is 49.

The square root of 66788905 is about 8172.4479196872. The cubic root of 66788905 is about 405.7278078014.

The spelling of 66788905 in words is "sixty-six million, seven hundred eighty-eight thousand, nine hundred five".