21395599 has 2 divisors, whose sum is σ = 21395600. Its totient is φ = 21395598.

The previous prime is 21395597. The next prime is 21395603. The reversal of 21395599 is 99559312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21395599 - 2¹ = 21395597 is a prime.

Together with 21395597, it forms a pair of twin primes.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21395593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697799 + 10697800.

It is an arithmetic number, because the mean of its divisors is an integer number (10697800).

Almost surely, 2^21395599 is an apocalyptic number.

21395599 is a deficient number, since it is larger than the sum of its proper divisors (1).

21395599 is an equidigital number, since it uses as much as digits as its factorization.

21395599 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 109350, while the sum is 43.

The square root of 21395599 is about 4625.5376984736. The cubic root of 21395599 is about 277.6140764108.

The spelling of 21395599 in words is "twenty-one million, three hundred ninety-five thousand, five hundred ninety-nine".