817729920 has 384 divisors, whose sum is σ = 3419807040. Its totient is φ = 175767552.

The previous prime is 817729901. The next prime is 817729921. The reversal of 817729920 is 29927718.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (817729921) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 684844 + ... + 686036.

Almost surely, 2^817729920 is an apocalyptic number.

817729920 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 817729920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1709903520).

817729920 is an abundant number, since it is smaller than the sum of its proper divisors (2602077120).

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

817729920 is a wasteful number, since it uses less digits than its factorization.

817729920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1242 (or 1227 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 817729920 is about 28595.9773394791. The cubic root of 817729920 is about 935.1256353621.

The spelling of 817729920 in words is "eight hundred seventeen million, seven hundred twenty-nine thousand, nine hundred twenty".