8391640 has 32 divisors (see below), whose sum is σ = 18996480. Its totient is φ = 3336192.

The previous prime is 8391623. The next prime is 8391641. The reversal of 8391640 is 461938.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8391641) 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, 7177 + ... + 8263.

It is an arithmetic number, because the mean of its divisors is an integer number (593640).

Almost surely, 2^8391640 is an apocalyptic number.

It is an amenable number.

8391640 is an abundant number, since it is smaller than the sum of its proper divisors (10604840).

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

8391640 is a wasteful number, since it uses less digits than its factorization.

8391640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1291 (or 1287 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 8391640 is about 2896.8327531979. The cubic root of 8391640 is about 203.2118118870.

The spelling of 8391640 in words is "eight million, three hundred ninety-one thousand, six hundred forty".