21438245 has 8 divisors (see below), whose sum is σ = 25769880. Its totient is φ = 17121280.

The previous prime is 21438239. The next prime is 21438253. The reversal of 21438245 is 54283412.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9728161 + 11710084 = 3119^2 + 3422^2 .

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

It is not a de Polignac number, because 21438245 - 2¹⁴ = 21421861 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140 + ... + 6549.

It is an arithmetic number, because the mean of its divisors is an integer number (3221235).

Almost surely, 2^21438245 is an apocalyptic number.

It is an amenable number.

21438245 is a deficient number, since it is larger than the sum of its proper divisors (4331635).

21438245 is an equidigital number, since it uses as much as digits as its factorization.

21438245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7335.

The product of its digits is 7680, while the sum is 29.

The square root of 21438245 is about 4630.1452461019. The cubic root of 21438245 is about 277.7984020538.

The spelling of 21438245 in words is "twenty-one million, four hundred thirty-eight thousand, two hundred forty-five".