218921901 has 16 divisors (see below), whose sum is σ = 325839360. Its totient is φ = 129593520.

The previous prime is 218921887. The next prime is 218921917. The reversal of 218921901 is 109129812.

It is not a de Polignac number, because 218921901 - 2⁹ = 218921389 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218921201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75721 + ... + 78558.

It is an arithmetic number, because the mean of its divisors is an integer number (20364960).

Almost surely, 2^218921901 is an apocalyptic number.

It is an amenable number.

218921901 is a deficient number, since it is larger than the sum of its proper divisors (106917459).

218921901 is a wasteful number, since it uses less digits than its factorization.

218921901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154336.

The product of its (nonzero) digits is 2592, while the sum is 33.

The square root of 218921901 is about 14796.0096309782. The cubic root of 218921901 is about 602.6933555248.

It can be divided in two parts, 2189 and 21901, that added together give a triangular number (24090 = T₂₁₉).

The spelling of 218921901 in words is "two hundred eighteen million, nine hundred twenty-one thousand, nine hundred one".