218101921 has 2 divisors, whose sum is σ = 218101922. Its totient is φ = 218101920.

The previous prime is 218101913. The next prime is 218101927. The reversal of 218101921 is 129101812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 173211921 + 44890000 = 13161^2 + 6700^2 .

It is a cyclic number.

It is not a de Polignac number, because 218101921 - 2³ = 218101913 is a prime.

It is not a weakly prime, because it can be changed into another prime (218101927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109050960 + 109050961.

It is an arithmetic number, because the mean of its divisors is an integer number (109050961).

Almost surely, 2^218101921 is an apocalyptic number.

It is an amenable number.

218101921 is a deficient number, since it is larger than the sum of its proper divisors (1).

218101921 is an equidigital number, since it uses as much as digits as its factorization.

218101921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 25.

The square root of 218101921 is about 14768.2741374881. The cubic root of 218101921 is about 601.9399440831.

The spelling of 218101921 in words is "two hundred eighteen million, one hundred one thousand, nine hundred twenty-one".