218540931 has 24 divisors (see below), whose sum is σ = 340369344. Its totient is φ = 124362000.

The previous prime is 218540887. The next prime is 218540977. The reversal of 218540931 is 139045812.

It is not a de Polignac number, because 218540931 - 2⁶ = 218540867 is a prime.

It is a super-2 number, since 2×218540931² = 95520277044693522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 218540892 and 218540901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218540431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33936 + ... + 39858.

It is an arithmetic number, because the mean of its divisors is an integer number (14182056).

Almost surely, 2^218540931 is an apocalyptic number.

218540931 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

218540931 is a deficient number, since it is larger than the sum of its proper divisors (121828413).

218540931 is a wasteful number, since it uses less digits than its factorization.

218540931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6191 (or 6184 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 218540931 is about 14783.1299459891. The cubic root of 218540931 is about 602.3435482735.

The spelling of 218540931 in words is "two hundred eighteen million, five hundred forty thousand, nine hundred thirty-one".