21445145 has 8 divisors (see below), whose sum is σ = 25776456. Its totient is φ = 17127936.

The previous prime is 21445141. The next prime is 21445147. The reversal of 21445145 is 54154412.

It can be written as a sum of positive squares in 4 ways, for example, as 3433609 + 18011536 = 1853^2 + 4244^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21445145 - 2² = 21445141 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21445141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 179 + ... + 6551.

It is an arithmetic number, because the mean of its divisors is an integer number (3222057).

Almost surely, 2^21445145 is an apocalyptic number.

It is an amenable number.

21445145 is a deficient number, since it is larger than the sum of its proper divisors (4331311).

21445145 is an equidigital number, since it uses as much as digits as its factorization.

21445145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7051.

The product of its digits is 3200, while the sum is 26.

The square root of 21445145 is about 4630.8903031707. The cubic root of 21445145 is about 277.8282024311.

Adding to 21445145 its reverse (54154412), we get a palindrome (75599557).

The spelling of 21445145 in words is "twenty-one million, four hundred forty-five thousand, one hundred forty-five".