21154445 has 8 divisors (see below), whose sum is σ = 27338136. Its totient is φ = 15621696.

The previous prime is 21154403. The next prime is 21154447. The reversal of 21154445 is 54445112.

It can be written as a sum of positive squares in 4 ways, for example, as 1110916 + 20043529 = 1054^2 + 4477^2 .

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 21154445 - 2⁶ = 21154381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 162662 + ... + 162791.

It is an arithmetic number, because the mean of its divisors is an integer number (3417267).

Almost surely, 2^21154445 is an apocalyptic number.

It is an amenable number.

21154445 is a deficient number, since it is larger than the sum of its proper divisors (6183691).

21154445 is a wasteful number, since it uses less digits than its factorization.

21154445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325471.

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

The square root of 21154445 is about 4599.3961560187. The cubic root of 21154445 is about 276.5671187478.

Adding to 21154445 its reverse (54445112), we get a palindrome (75599557).

The spelling of 21154445 in words is "twenty-one million, one hundred fifty-four thousand, four hundred forty-five".