21550447 has 2 divisors, whose sum is σ = 21550448. Its totient is φ = 21550446.

The previous prime is 21550409. The next prime is 21550453. The reversal of 21550447 is 74405512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21550447 - 2¹¹ = 21548399 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 (21550457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775223 + 10775224.

It is an arithmetic number, because the mean of its divisors is an integer number (10775224).

Almost surely, 2^21550447 is an apocalyptic number.

21550447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21550447 is an equidigital number, since it uses as much as digits as its factorization.

21550447 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5600, while the sum is 28.

The square root of 21550447 is about 4642.2459004236. The cubic root of 21550447 is about 278.2821996815.

Adding to 21550447 its reverse (74405512), we get a palindrome (95955959).

The spelling of 21550447 in words is "twenty-one million, five hundred fifty thousand, four hundred forty-seven".