21918101 has 2 divisors, whose sum is σ = 21918102. Its totient is φ = 21918100.

The previous prime is 21918079. The next prime is 21918107. The reversal of 21918101 is 10181912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20295025 + 1623076 = 4505^2 + 1274^2 .

It is a cyclic number.

It is not a de Polignac number, because 21918101 - 2⁶ = 21918037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21918107) 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 as a sum of consecutive naturals, namely, 10959050 + 10959051.

It is an arithmetic number, because the mean of its divisors is an integer number (10959051).

Almost surely, 2^21918101 is an apocalyptic number.

It is an amenable number.

21918101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21918101 is an equidigital number, since it uses as much as digits as its factorization.

21918101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 23.

The square root of 21918101 is about 4681.6771567463. The cubic root of 21918101 is about 279.8557973457.

The spelling of 21918101 in words is "twenty-one million, nine hundred eighteen thousand, one hundred one".