21138101 has 2 divisors, whose sum is σ = 21138102. Its totient is φ = 21138100.

The previous prime is 21138077. The next prime is 21138113. The reversal of 21138101 is 10183112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16080100 + 5058001 = 4010^2 + 2249^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21138101 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21138101.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21138121) 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, 10569050 + 10569051.

It is an arithmetic number, because the mean of its divisors is an integer number (10569051).

Almost surely, 2^21138101 is an apocalyptic number.

It is an amenable number.

21138101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21138101 is an equidigital number, since it uses as much as digits as its factorization.

21138101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 17.

The square root of 21138101 is about 4597.6190577298. The cubic root of 21138101 is about 276.4958748146.

The spelling of 21138101 in words is "twenty-one million, one hundred thirty-eight thousand, one hundred one".