218672409 has 4 divisors (see below), whose sum is σ = 291563216. Its totient is φ = 145781604.

The previous prime is 218672407. The next prime is 218672423. The reversal of 218672409 is 904276812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 218672409 - 2¹ = 218672407 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (218672407) 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, 36445399 + ... + 36445404.

It is an arithmetic number, because the mean of its divisors is an integer number (72890804).

Almost surely, 2^218672409 is an apocalyptic number.

It is an amenable number.

218672409 is a deficient number, since it is larger than the sum of its proper divisors (72890807).

218672409 is an equidigital number, since it uses as much as digits as its factorization.

218672409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72890806.

The product of its (nonzero) digits is 48384, while the sum is 39.

The square root of 218672409 is about 14787.5761705561. The cubic root of 218672409 is about 602.4643174864.

The spelling of 218672409 in words is "two hundred eighteen million, six hundred seventy-two thousand, four hundred nine".