816565920 has 48 divisors (see below), whose sum is σ = 2572184160. Its totient is φ = 217750784.

The previous prime is 816565873. The next prime is 816565927. The reversal of 816565920 is 29565618.

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (816565927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 850110 + ... + 851069.

It is an arithmetic number, because the mean of its divisors is an integer number (53587170).

Almost surely, 2^816565920 is an apocalyptic number.

816565920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

816565920 is an abundant number, since it is smaller than the sum of its proper divisors (1755618240).

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

816565920 is a wasteful number, since it uses less digits than its factorization.

816565920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1701197 (or 1701189 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 42.

The square root of 816565920 is about 28575.6175786281. The cubic root of 816565920 is about 934.6817222430.

The spelling of 816565920 in words is "eight hundred sixteen million, five hundred sixty-five thousand, nine hundred twenty".