647820 has 72 divisors (see below), whose sum is σ = 2031120. Its totient is φ = 167040.

The previous prime is 647809. The next prime is 647821. The reversal of 647820 is 28746.

647820 = T₅₁ + T₅₂ + ... + T₁₅₈.

It is not an unprimeable number, because it can be changed into a prime (647821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10590 + ... + 10650.

It is an arithmetic number, because the mean of its divisors is an integer number (28210).

2⁶⁴⁷⁸²⁰ is an apocalyptic number.

647820 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 647820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1015560).

647820 is an abundant number, since it is smaller than the sum of its proper divisors (1383300).

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

647820 is a wasteful number, since it uses less digits than its factorization.

647820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 647820 is about 804.8726607358. The cubic root of 647820 is about 86.5269609788.

The spelling of 647820 in words is "six hundred forty-seven thousand, eight hundred twenty".