21545149 has 2 divisors, whose sum is σ = 21545150. Its totient is φ = 21545148.

The previous prime is 21545141. The next prime is 21545179. The reversal of 21545149 is 94154512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20313049 + 1232100 = 4507^2 + 1110^2 .

It is a cyclic number.

It is not a de Polignac number, because 21545149 - 2³ = 21545141 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21545149.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21545141) 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, 10772574 + 10772575.

It is an arithmetic number, because the mean of its divisors is an integer number (10772575).

Almost surely, 2^21545149 is an apocalyptic number.

It is an amenable number.

21545149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545149 is an equidigital number, since it uses as much as digits as its factorization.

21545149 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7200, while the sum is 31.

The square root of 21545149 is about 4641.6752363775. The cubic root of 21545149 is about 278.2593933498.

The spelling of 21545149 in words is "twenty-one million, five hundred forty-five thousand, one hundred forty-nine".