21244997 has 4 divisors (see below), whose sum is σ = 21645900. Its totient is φ = 20844096.

The previous prime is 21244991. The next prime is 21244999. The reversal of 21244997 is 79944212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15124321 + 6120676 = 3889^2 + 2474^2 .

It is a cyclic number.

It is not a de Polignac number, because 21244997 - 2²⁴ = 4467781 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21244997.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21244991) 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, 200372 + ... + 200477.

It is an arithmetic number, because the mean of its divisors is an integer number (5411475).

Almost surely, 2^21244997 is an apocalyptic number.

It is an amenable number.

21244997 is a deficient number, since it is larger than the sum of its proper divisors (400903).

21244997 is an equidigital number, since it uses as much as digits as its factorization.

21244997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 400902.

The product of its digits is 36288, while the sum is 38.

The square root of 21244997 is about 4609.2295451626. The cubic root of 21244997 is about 276.9611739471.

The spelling of 21244997 in words is "twenty-one million, two hundred forty-four thousand, nine hundred ninety-seven".