817206640 has 40 divisors (see below), whose sum is σ = 1932220080. Its totient is φ = 321340416.

The previous prime is 817206623. The next prime is 817206647. The reversal of 817206640 is 46602718.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 817206596 and 817206605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (817206647) 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, 81849 + ... + 91288.

It is an arithmetic number, because the mean of its divisors is an integer number (48305502).

Almost surely, 2^817206640 is an apocalyptic number.

817206640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

817206640 is an abundant number, since it is smaller than the sum of its proper divisors (1115013440).

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

817206640 is a wasteful number, since it uses less digits than its factorization.

817206640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173209 (or 173203 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 817206640 is about 28586.8263366188. The cubic root of 817206640 is about 934.9261249267.

The spelling of 817206640 in words is "eight hundred seventeen million, two hundred six thousand, six hundred forty".