21235549 has 2 divisors, whose sum is σ = 21235550. Its totient is φ = 21235548.

The previous prime is 21235537. The next prime is 21235573. The reversal of 21235549 is 94553212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16867449 + 4368100 = 4107^2 + 2090^2 .

It is a cyclic number.

It is not a de Polignac number, because 21235549 - 2⁵ = 21235517 is a prime.

It is equal to p_1343857 and since 21235549 and 1343857 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21235549.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21235849) 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, 10617774 + 10617775.

It is an arithmetic number, because the mean of its divisors is an integer number (10617775).

Almost surely, 2^21235549 is an apocalyptic number.

It is an amenable number.

21235549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21235549 is an equidigital number, since it uses as much as digits as its factorization.

21235549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10800, while the sum is 31.

The square root of 21235549 is about 4608.2045310511. The cubic root of 21235549 is about 276.9201114612.

The spelling of 21235549 in words is "twenty-one million, two hundred thirty-five thousand, five hundred forty-nine".