647791 has 4 divisors (see below), whose sum is σ = 649512. Its totient is φ = 646072.

The previous prime is 647789. The next prime is 647809. The reversal of 647791 is 197746.

647791 is nontrivially palindromic in base 5.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 197746 = 2 ⋅98873.

It is a cyclic number.

It is not a de Polignac number, because 647791 - 2¹ = 647789 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 (647741) 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, 25 + ... + 1138.

It is an arithmetic number, because the mean of its divisors is an integer number (162378).

2⁶⁴⁷⁷⁹¹ is an apocalyptic number.

647791 is a deficient number, since it is larger than the sum of its proper divisors (1721).

647791 is a wasteful number, since it uses less digits than its factorization.

647791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1720.

The product of its digits is 10584, while the sum is 34.

The square root of 647791 is about 804.8546452621. The cubic root of 647791 is about 86.5256698180.

The spelling of 647791 in words is "six hundred forty-seven thousand, seven hundred ninety-one".