21542241 has 16 divisors (see below), whose sum is σ = 33886208. Its totient is φ = 11912400.

The previous prime is 21542233. The next prime is 21542263. The reversal of 21542241 is 14224512.

It is not a de Polignac number, because 21542241 - 2³ = 21542233 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21542231) 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, 15895 + ... + 17196.

It is an arithmetic number, because the mean of its divisors is an integer number (2117888).

Almost surely, 2^21542241 is an apocalyptic number.

21542241 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21542241 is a deficient number, since it is larger than the sum of its proper divisors (12343967).

21542241 is a wasteful number, since it uses less digits than its factorization.

21542241 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33132.

The product of its digits is 640, while the sum is 21.

The square root of 21542241 is about 4641.3619768340. The cubic root of 21542241 is about 278.2468736758.

Adding to 21542241 its reverse (14224512), we get a palindrome (35766753).

The spelling of 21542241 in words is "twenty-one million, five hundred forty-two thousand, two hundred forty-one".