815220 has 72 divisors (see below), whose sum is σ = 2830464. Its totient is φ = 186048.

The previous prime is 815209. The next prime is 815231. The reversal of 815220 is 22518.

It is an interprime number because it is at equal distance from previous prime (815209) and next prime (815231).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 815193 and 815202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 937 + ... + 1583.

It is an arithmetic number, because the mean of its divisors is an integer number (39312).

2⁸¹⁵²²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 815220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1415232).

815220 is an abundant number, since it is smaller than the sum of its proper divisors (2015244).

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

815220 is a wasteful number, since it uses less digits than its factorization.

815220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669 (or 664 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 815220 is about 902.8953427724. The cubic root of 815220 is about 93.4167904312.

Adding to 815220 its reverse (22518), we get a palindrome (837738).

It can be divided in two parts, 815 and 220, that added together give a triangular number (1035 = T₄₅).

The spelling of 815220 in words is "eight hundred fifteen thousand, two hundred twenty".