21543949 has 8 divisors (see below), whose sum is σ = 24693120. Its totient is φ = 18412656.

The previous prime is 21543931. The next prime is 21543961. The reversal of 21543949 is 94934512.

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 21543949 - 2¹¹ = 21541901 is a prime.

It is a Duffinian number.

21543949 is a modest number, since divided by 3949 gives 2154 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21544949) 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, 1774 + ... + 6799.

It is an arithmetic number, because the mean of its divisors is an integer number (3086640).

Almost surely, 2^21543949 is an apocalyptic number.

It is an amenable number.

21543949 is a deficient number, since it is larger than the sum of its proper divisors (3149171).

21543949 is an equidigital number, since it uses as much as digits as its factorization.

21543949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8939.

The product of its digits is 38880, while the sum is 37.

The square root of 21543949 is about 4641.5459709024. The cubic root of 21543949 is about 278.2542271834.

The spelling of 21543949 in words is "twenty-one million, five hundred forty-three thousand, nine hundred forty-nine".