647663771 has 4 divisors (see below), whose sum is σ = 647875200. Its totient is φ = 647452344.

The previous prime is 647663761. The next prime is 647663791. The reversal of 647663771 is 177366746.

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 647663771 - 2¹⁴ = 647647387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (647663761) 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, 101051 + ... + 107268.

It is an arithmetic number, because the mean of its divisors is an integer number (161968800).

Almost surely, 2^647663771 is an apocalyptic number.

647663771 is a deficient number, since it is larger than the sum of its proper divisors (211429).

647663771 is a wasteful number, since it uses less digits than its factorization.

647663771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211428.

The product of its digits is 889056, while the sum is 47.

The square root of 647663771 is about 25449.2391045391. The cubic root of 647663771 is about 865.2000477318.

The spelling of 647663771 in words is "six hundred forty-seven million, six hundred sixty-three thousand, seven hundred seventy-one".