21581241 has 8 divisors (see below), whose sum is σ = 31390944. Its totient is φ = 13079520.

The previous prime is 21581233. The next prime is 21581257. The reversal of 21581241 is 14218512.

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

It is not a de Polignac number, because 21581241 - 2³ = 21581233 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21581201) 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, 326956 + ... + 327021.

It is an arithmetic number, because the mean of its divisors is an integer number (3923868).

Almost surely, 2^21581241 is an apocalyptic number.

It is an amenable number.

21581241 is a deficient number, since it is larger than the sum of its proper divisors (9809703).

21581241 is a wasteful number, since it uses less digits than its factorization.

21581241 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653991.

The product of its digits is 640, while the sum is 24.

The square root of 21581241 is about 4645.5614300104. The cubic root of 21581241 is about 278.4146848468.

Adding to 21581241 its reverse (14218512), we get a palindrome (35799753).

The spelling of 21581241 in words is "twenty-one million, five hundred eighty-one thousand, two hundred forty-one".