21599243 has 2 divisors, whose sum is σ = 21599244. Its totient is φ = 21599242.

The previous prime is 21599213. The next prime is 21599269. The reversal of 21599243 is 34299512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21599243 - 2⁸ = 21598987 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21599213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10799621 + 10799622.

It is an arithmetic number, because the mean of its divisors is an integer number (10799622).

Almost surely, 2^21599243 is an apocalyptic number.

21599243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21599243 is an equidigital number, since it uses as much as digits as its factorization.

21599243 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 35.

The square root of 21599243 is about 4647.4985745022. The cubic root of 21599243 is about 278.4920765688.

The spelling of 21599243 in words is "twenty-one million, five hundred ninety-nine thousand, two hundred forty-three".