21438101 has 2 divisors, whose sum is σ = 21438102. Its totient is φ = 21438100.

The previous prime is 21438089. The next prime is 21438103. The reversal of 21438101 is 10183412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21298225 + 139876 = 4615^2 + 374^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21438101 is a prime.

Together with 21438103, it forms a pair of twin primes.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21438103) 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, 10719050 + 10719051.

It is an arithmetic number, because the mean of its divisors is an integer number (10719051).

Almost surely, 2^21438101 is an apocalyptic number.

It is an amenable number.

21438101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21438101 is an equidigital number, since it uses as much as digits as its factorization.

21438101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21438101 is about 4630.1296958077. The cubic root of 21438101 is about 277.7977800648.

The spelling of 21438101 in words is "twenty-one million, four hundred thirty-eight thousand, one hundred one".