21475549 has 2 divisors, whose sum is σ = 21475550. Its totient is φ = 21475548.

The previous prime is 21475543. The next prime is 21475579. The reversal of 21475549 is 94557412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15920100 + 5555449 = 3990^2 + 2357^2 .

It is a cyclic number.

It is not a de Polignac number, because 21475549 - 2¹³ = 21467357 is a prime.

It is a super-2 number, since 2×21475549² = 922398409702802, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21475543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10737774 + 10737775.

It is an arithmetic number, because the mean of its divisors is an integer number (10737775).

Almost surely, 2^21475549 is an apocalyptic number.

It is an amenable number.

21475549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21475549 is an equidigital number, since it uses as much as digits as its factorization.

21475549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50400, while the sum is 37.

The square root of 21475549 is about 4634.1718785561. The cubic root of 21475549 is about 277.9594380377.

The spelling of 21475549 in words is "twenty-one million, four hundred seventy-five thousand, five hundred forty-nine".