815990400 has 288 divisors, whose sum is σ = 3015125100. Its totient is φ = 209879040.

The previous prime is 815990393. The next prime is 815990407. The reversal of 815990400 is 4099518.

It is an interprime number because it is at equal distance from previous prime (815990393) and next prime (815990407).

It can be written as a sum of positive squares in 6 ways, for example, as 516561984 + 299428416 = 22728^2 + 17304^2 .

It is a tau number, because it is divible by the number of its divisors (288).

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 (815990407) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 834712 + ... + 835688.

Almost surely, 2^815990400 is an apocalyptic number.

815990400 is a gapful number since it is divisible by the number (80) 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 815990400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1507562550).

815990400 is an abundant number, since it is smaller than the sum of its proper divisors (2199134700).

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

815990400 is a wasteful number, since it uses less digits than its factorization.

815990400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1036 (or 1016 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 815990400 is about 28565.5456800671. The cubic root of 815990400 is about 934.4620810851.

The spelling of 815990400 in words is "eight hundred fifteen million, nine hundred ninety thousand, four hundred".