7218640 has 80 divisors (see below), whose sum is σ = 19748736. Its totient is φ = 2419200.

The previous prime is 7218637. The next prime is 7218649. The reversal of 7218640 is 468127.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 7218599 and 7218608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7218649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11125 + ... + 11755.

Almost surely, 2^7218640 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 7218640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9874368).

7218640 is an abundant number, since it is smaller than the sum of its proper divisors (12530096).

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

7218640 is a wasteful number, since it uses less digits than its factorization.

7218640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 668 (or 662 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 7218640 is about 2686.7526867950. The cubic root of 7218640 is about 193.2643696426.

The spelling of 7218640 in words is "seven million, two hundred eighteen thousand, six hundred forty".