21436637 has 2 divisors, whose sum is σ = 21436638. Its totient is φ = 21436636.

The previous prime is 21436601. The next prime is 21436651. The reversal of 21436637 is 73663412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19061956 + 2374681 = 4366^2 + 1541^2 .

It is a cyclic number.

It is not a de Polignac number, because 21436637 - 2⁶ = 21436573 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21436697) 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, 10718318 + 10718319.

It is an arithmetic number, because the mean of its divisors is an integer number (10718319).

Almost surely, 2^21436637 is an apocalyptic number.

It is an amenable number.

21436637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21436637 is an equidigital number, since it uses as much as digits as its factorization.

21436637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 32.

The square root of 21436637 is about 4629.9715981850. The cubic root of 21436637 is about 277.7914563516.

The spelling of 21436637 in words is "twenty-one million, four hundred thirty-six thousand, six hundred thirty-seven".