7857640 has 96 divisors (see below), whose sum is σ = 21751200. Its totient is φ = 2540160.

The previous prime is 7857613. The next prime is 7857643. The reversal of 7857640 is 467587.

It is a happy number.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 7857640.

It is not an unprimeable number, because it can be changed into a prime (7857643) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 37135 + ... + 37345.

It is an arithmetic number, because the mean of its divisors is an integer number (226575).

Almost surely, 2^7857640 is an apocalyptic number.

7857640 is a gapful number since it is divisible by the number (70) 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 7857640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10875600).

7857640 is an abundant number, since it is smaller than the sum of its proper divisors (13893560).

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

7857640 is a wasteful number, since it uses less digits than its factorization.

7857640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255 (or 244 counting only the distinct ones).

The product of its (nonzero) digits is 47040, while the sum is 37.

The square root of 7857640 is about 2803.1482301156. The cubic root of 7857640 is about 198.8065593286.

The spelling of 7857640 in words is "seven million, eight hundred fifty-seven thousand, six hundred forty".