21241399 has 2 divisors, whose sum is σ = 21241400. Its totient is φ = 21241398.

The previous prime is 21241391. The next prime is 21241421. The reversal of 21241399 is 99314212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21241399 - 2³ = 21241391 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21241399.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21241391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620699 + 10620700.

It is an arithmetic number, because the mean of its divisors is an integer number (10620700).

Almost surely, 2^21241399 is an apocalyptic number.

21241399 is a deficient number, since it is larger than the sum of its proper divisors (1).

21241399 is an equidigital number, since it uses as much as digits as its factorization.

21241399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 31.

The square root of 21241399 is about 4608.8392247940. The cubic root of 21241399 is about 276.9455379119.

The spelling of 21241399 in words is "twenty-one million, two hundred forty-one thousand, three hundred ninety-nine".