647991885 has 8 divisors (see below), whose sum is σ = 1036787040. Its totient is φ = 345595664.

The previous prime is 647991881. The next prime is 647991889. The reversal of 647991885 is 588199746.

It is an interprime number because it is at equal distance from previous prime (647991881) and next prime (647991889).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 647991885 - 2² = 647991881 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647991881) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21599715 + ... + 21599744.

It is an arithmetic number, because the mean of its divisors is an integer number (129598380).

Almost surely, 2^647991885 is an apocalyptic number.

It is an amenable number.

647991885 is a deficient number, since it is larger than the sum of its proper divisors (388795155).

647991885 is a wasteful number, since it uses less digits than its factorization.

647991885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43199467.

The product of its digits is 4354560, while the sum is 57.

The square root of 647991885 is about 25455.6847285631. The cubic root of 647991885 is about 865.3461298684.

The spelling of 647991885 in words is "six hundred forty-seven million, nine hundred ninety-one thousand, eight hundred eighty-five".