815219820 has 144 divisors (see below), whose sum is σ = 2619751680. Its totient is φ = 204766848.

The previous prime is 815219791. The next prime is 815219827. The reversal of 815219820 is 28912518.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (815219827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 275911 + ... + 278849.

It is an arithmetic number, because the mean of its divisors is an integer number (18192720).

Almost surely, 2^815219820 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 815219820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1309875840).

815219820 is an abundant number, since it is smaller than the sum of its proper divisors (1804531860).

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

815219820 is a wasteful number, since it uses less digits than its factorization.

815219820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3044 (or 3039 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 36.

The square root of 815219820 is about 28552.0545670535. The cubic root of 815219820 is about 934.1678355573.

It can be divided in two parts, 8152 and 19820, that added together give a palindrome (27972).

The spelling of 815219820 in words is "eight hundred fifteen million, two hundred nineteen thousand, eight hundred twenty".