21445505 has 4 divisors (see below), whose sum is σ = 25734612. Its totient is φ = 17156400.

The previous prime is 21445493. The next prime is 21445507. The reversal of 21445505 is 50554412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12397441 + 9048064 = 3521^2 + 3008^2 .

It is not a de Polignac number, because 21445505 - 2⁶ = 21445441 is a prime.

It is a Duffinian number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21445507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2144546 + ... + 2144555.

It is an arithmetic number, because the mean of its divisors is an integer number (6433653).

Almost surely, 2^21445505 is an apocalyptic number.

It is an amenable number.

21445505 is a deficient number, since it is larger than the sum of its proper divisors (4289107).

21445505 is an equidigital number, since it uses as much as digits as its factorization.

21445505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4289106.

The product of its (nonzero) digits is 4000, while the sum is 26.

The square root of 21445505 is about 4630.9291724232. The cubic root of 21445505 is about 277.8297570579.

Adding to 21445505 its reverse (50554412), we get a palindrome (71999917).

The spelling of 21445505 in words is "twenty-one million, four hundred forty-five thousand, five hundred five".