21248109 has 16 divisors (see below), whose sum is σ = 31628800. Its totient is φ = 14097888.

The previous prime is 21248107. The next prime is 21248119. The reversal of 21248109 is 90184212.

It is not a de Polignac number, because 21248109 - 2¹ = 21248107 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21248107) 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 15 ways as a sum of consecutive naturals, for example, 4257 + ... + 7785.

It is an arithmetic number, because the mean of its divisors is an integer number (1976800).

Almost surely, 2^21248109 is an apocalyptic number.

It is an amenable number.

21248109 is a deficient number, since it is larger than the sum of its proper divisors (10380691).

21248109 is a wasteful number, since it uses less digits than its factorization.

21248109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3761 (or 3755 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21248109 is about 4609.5671163353. The cubic root of 21248109 is about 276.9746965205.

The spelling of 21248109 in words is "twenty-one million, two hundred forty-eight thousand, one hundred nine".