218405923 has 2 divisors, whose sum is σ = 218405924. Its totient is φ = 218405922.

The previous prime is 218405917. The next prime is 218405981. The reversal of 218405923 is 329504812.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-218405923 is a prime.

It is a super-2 number, since 2×218405923² = 95402294402963858, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (218405023) 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 as a sum of consecutive naturals, namely, 109202961 + 109202962.

It is an arithmetic number, because the mean of its divisors is an integer number (109202962).

Almost surely, 2^218405923 is an apocalyptic number.

218405923 is a deficient number, since it is larger than the sum of its proper divisors (1).

218405923 is an equidigital number, since it uses as much as digits as its factorization.

218405923 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 218405923 is about 14778.5629544959. The cubic root of 218405923 is about 602.2194861599.

The spelling of 218405923 in words is "two hundred eighteen million, four hundred five thousand, nine hundred twenty-three".