21516249 has 8 divisors (see below), whose sum is σ = 28984480. Its totient is φ = 14196096.

The previous prime is 21516241. The next prime is 21516259. The reversal of 21516249 is 94261512.

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

It is not a de Polignac number, because 21516249 - 2³ = 21516241 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 (21516241) by changing a digit.

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, 36679 + ... + 37260.

It is an arithmetic number, because the mean of its divisors is an integer number (3623060).

Almost surely, 2^21516249 is an apocalyptic number.

It is an amenable number.

21516249 is a deficient number, since it is larger than the sum of its proper divisors (7468231).

21516249 is an equidigital number, since it uses as much as digits as its factorization.

21516249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74039.

The product of its digits is 4320, while the sum is 30.

The square root of 21516249 is about 4638.5610915455. The cubic root of 21516249 is about 278.1349214825.

The spelling of 21516249 in words is "twenty-one million, five hundred sixteen thousand, two hundred forty-nine".