21242361 has 16 divisors (see below), whose sum is σ = 34073600. Its totient is φ = 11499408.

The previous prime is 21242357. The next prime is 21242369. The reversal of 21242361 is 16324212.

It is not a de Polignac number, because 21242361 - 2² = 21242357 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 (21242369) 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, 26221 + ... + 27018.

It is an arithmetic number, because the mean of its divisors is an integer number (2129600).

Almost surely, 2^21242361 is an apocalyptic number.

21242361 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21242361 is a deficient number, since it is larger than the sum of its proper divisors (12831239).

21242361 is a wasteful number, since it uses less digits than its factorization.

21242361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53268.

The product of its digits is 576, while the sum is 21.

The square root of 21242361 is about 4608.9435882857. The cubic root of 21242361 is about 276.9497187034.

Adding to 21242361 its reverse (16324212), we get a palindrome (37566573).

The spelling of 21242361 in words is "twenty-one million, two hundred forty-two thousand, three hundred sixty-one".