815920128 has 154 divisors (see below), whose sum is σ = 2447683874. Its totient is φ = 271724544.

The previous prime is 815920087. The next prime is 815920169. The reversal of 815920128 is 821029518.

It is an interprime number because it is at equal distance from previous prime (815920087) and next prime (815920169).

It can be written as a sum of positive squares in only one way, i.e., 812934144 + 2985984 = 28512^2 + 1728^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 815920092 and 815920101.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 745950 + ... + 747042.

Almost surely, 2^815920128 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 815920128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1223841937).

815920128 is an abundant number, since it is smaller than the sum of its proper divisors (1631763746).

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

815920128 is an equidigital number, since it uses as much as digits as its factorization.

815920128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1131 (or 1098 counting only the distinct ones).

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

The square root of 815920128 is about 28564.3156403230. The cubic root of 815920128 is about 934.4352554409.

The spelling of 815920128 in words is "eight hundred fifteen million, nine hundred twenty thousand, one hundred twenty-eight".