815121000 has 288 divisors, whose sum is σ = 2883633480. Its totient is φ = 207552000.

The previous prime is 815120987. The next prime is 815121001. The reversal of 815121000 is 121518.

It can be written as a sum of positive squares in 4 ways, for example, as 66879684 + 748241316 = 8178^2 + 27354^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815121001) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 17342977 + ... + 17343023.

Almost surely, 2^815121000 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 815121000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1441816740).

815121000 is an abundant number, since it is smaller than the sum of its proper divisors (2068512480).

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

815121000 is a wasteful number, since it uses less digits than its factorization.

815121000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162 (or 98 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 815121000 is about 28550.3239911564. The cubic root of 815121000 is about 934.1300877853.

Adding to 815121000 its reverse (121518), we get a palindrome (815242518).

The spelling of 815121000 in words is "eight hundred fifteen million, one hundred twenty-one thousand".