21442237 has 4 divisors (see below), whose sum is σ = 21471840. Its totient is φ = 21412636.

The previous prime is 21442229. The next prime is 21442243. The reversal of 21442237 is 73224412.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21442237 - 2³ = 21442229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21442037) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13687 + ... + 15172.

It is an arithmetic number, because the mean of its divisors is an integer number (5367960).

Almost surely, 2^21442237 is an apocalyptic number.

It is an amenable number.

21442237 is a deficient number, since it is larger than the sum of its proper divisors (29603).

21442237 is an equidigital number, since it uses as much as digits as its factorization.

21442237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29602.

The product of its digits is 2688, while the sum is 25.

The square root of 21442237 is about 4630.5763140240. The cubic root of 21442237 is about 277.8156438631.

Adding to 21442237 its reverse (73224412), we get a palindrome (94666649).

The spelling of 21442237 in words is "twenty-one million, four hundred forty-two thousand, two hundred thirty-seven".