647666220 has 96 divisors (see below), whose sum is σ = 1866590208. Its totient is φ = 167726592.

The previous prime is 647666209. The next prime is 647666233. The reversal of 647666220 is 22666746.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 292357 + ... + 294563.

It is an arithmetic number, because the mean of its divisors is an integer number (19443648).

Almost surely, 2^647666220 is an apocalyptic number.

647666220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 647666220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (933295104).

647666220 is an abundant number, since it is smaller than the sum of its proper divisors (1218923988).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

647666220 is a wasteful number, since it uses less digits than its factorization.

647666220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2359 (or 2357 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 39.

The square root of 647666220 is about 25449.2872198810. The cubic root of 647666220 is about 865.2011382525.

The spelling of 647666220 in words is "six hundred forty-seven million, six hundred sixty-six thousand, two hundred twenty".