21244737 has 4 divisors (see below), whose sum is σ = 28326320. Its totient is φ = 14163156.

The previous prime is 21244723. The next prime is 21244757. The reversal of 21244737 is 73744212.

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 not a de Polignac number, because 21244737 - 2⁶ = 21244673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21244757) 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, 3540787 + ... + 3540792.

It is an arithmetic number, because the mean of its divisors is an integer number (7081580).

Almost surely, 2^21244737 is an apocalyptic number.

It is an amenable number.

21244737 is a deficient number, since it is larger than the sum of its proper divisors (7081583).

21244737 is an equidigital number, since it uses as much as digits as its factorization.

21244737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7081582.

The product of its digits is 9408, while the sum is 30.

The square root of 21244737 is about 4609.2013407965. The cubic root of 21244737 is about 276.9600441093.

Adding to 21244737 its reverse (73744212), we get a palindrome (94988949).

The spelling of 21244737 in words is "twenty-one million, two hundred forty-four thousand, seven hundred thirty-seven".