647685621 has 12 divisors (see below), whose sum is σ = 1020595680. Its totient is φ = 392536680.

The previous prime is 647685613. The next prime is 647685653. The reversal of 647685621 is 126586746.

It is not a de Polignac number, because 647685621 - 2³ = 647685613 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 (648685621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3271041 + ... + 3271238.

It is an arithmetic number, because the mean of its divisors is an integer number (85049640).

Almost surely, 2^647685621 is an apocalyptic number.

It is an amenable number.

647685621 is a deficient number, since it is larger than the sum of its proper divisors (372910059).

647685621 is a wasteful number, since it uses less digits than its factorization.

647685621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6542296 (or 6542293 counting only the distinct ones).

The product of its digits is 483840, while the sum is 45.

The square root of 647685621 is about 25449.6683868376. The cubic root of 647685621 is about 865.2097772702.

The spelling of 647685621 in words is "six hundred forty-seven million, six hundred eighty-five thousand, six hundred twenty-one".