8257640 has 32 divisors (see below), whose sum is σ = 18900000. Its totient is φ = 3246144.

The previous prime is 8257637. The next prime is 8257643. The reversal of 8257640 is 467528.

It is an interprime number because it is at equal distance from previous prime (8257637) and next prime (8257643).

It is a junction number, because it is equal to n+sod(n) for n = 8257597 and 8257606.

It is not an unprimeable number, because it can be changed into a prime (8257643) 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, 611 + ... + 4109.

It is an arithmetic number, because the mean of its divisors is an integer number (590625).

Almost surely, 2^8257640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8257640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9450000).

8257640 is an abundant number, since it is smaller than the sum of its proper divisors (10642360).

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

8257640 is a wasteful number, since it uses less digits than its factorization.

8257640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3569 (or 3565 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 32.

The square root of 8257640 is about 2873.6109687987. The cubic root of 8257640 is about 202.1243556734.

The spelling of 8257640 in words is "eight million, two hundred fifty-seven thousand, six hundred forty".