84218509 has 4 divisors (see below), whose sum is σ = 84238204. Its totient is φ = 84198816.

The previous prime is 84218471. The next prime is 84218539. The reversal of 84218509 is 90581248.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 62568100 + 21650409 = 7910^2 + 4653^2 .

It is a cyclic number.

It is not a de Polignac number, because 84218509 - 2⁹ = 84217997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (84218539) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 432 + ... + 12985.

It is an arithmetic number, because the mean of its divisors is an integer number (21059551).

Almost surely, 2^84218509 is an apocalyptic number.

It is an amenable number.

84218509 is a deficient number, since it is larger than the sum of its proper divisors (19695).

84218509 is a wasteful number, since it uses less digits than its factorization.

84218509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19694.

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 84218509 is about 9177.0642909375. The cubic root of 84218509 is about 438.3313329419.

The spelling of 84218509 in words is "eighty-four million, two hundred eighteen thousand, five hundred nine".