218531906 has 16 divisors (see below), whose sum is σ = 347371416. Its totient is φ = 102752256.

The previous prime is 218531897. The next prime is 218531921. The reversal of 218531906 is 609135812.

It can be written as a sum of positive squares in 4 ways, for example, as 149059681 + 69472225 = 12209^2 + 8335^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58610 + ... + 62226.

Almost surely, 2^218531906 is an apocalyptic number.

218531906 is a deficient number, since it is larger than the sum of its proper divisors (128839510).

218531906 is a wasteful number, since it uses less digits than its factorization.

218531906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5413.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 218531906 is about 14782.8246962480. The cubic root of 218531906 is about 602.3352565768.

The spelling of 218531906 in words is "two hundred eighteen million, five hundred thirty-one thousand, nine hundred six".