817745920 has 52 divisors (see below), whose sum is σ = 1962399780. Its totient is φ = 327090176.

The previous prime is 817745911. The next prime is 817745923. The reversal of 817745920 is 29547718.

It can be written as a sum of positive squares in 2 ways, for example, as 247873536 + 569872384 = 15744^2 + 23872^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (817745923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 516 + ... + 40444.

Almost surely, 2^817745920 is an apocalyptic number.

817745920 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 817745920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (981199890).

817745920 is an abundant number, since it is smaller than the sum of its proper divisors (1144653860).

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

817745920 is an equidigital number, since it uses as much as digits as its factorization.

817745920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39958 (or 39936 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 43.

The square root of 817745920 is about 28596.2570977392. The cubic root of 817745920 is about 935.1317343247.

The spelling of 817745920 in words is "eight hundred seventeen million, seven hundred forty-five thousand, nine hundred twenty".