21517449 has 16 divisors (see below), whose sum is σ = 29877120. Its totient is φ = 13758080.

The previous prime is 21517439. The next prime is 21517451. The reversal of 21517449 is 94471512.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21517449 - 2¹⁵ = 21484681 is a prime.

It is a super-2 number, since 2×21517449² = 926001222935202, which contains 22 as substring.

Its product of digits (10080) is a multiple of the sum of its prime divisors (1680).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21517429) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13789 + ... + 15269.

It is an arithmetic number, because the mean of its divisors is an integer number (1867320).

Almost surely, 2^21517449 is an apocalyptic number.

21517449 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21517449 is a deficient number, since it is larger than the sum of its proper divisors (8359671).

21517449 is a wasteful number, since it uses less digits than its factorization.

21517449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1680.

The product of its digits is 10080, while the sum is 33.

The square root of 21517449 is about 4638.6904401997. The cubic root of 21517449 is about 278.1400920818.

The spelling of 21517449 in words is "twenty-one million, five hundred seventeen thousand, four hundred forty-nine".