21181799 has 2 divisors, whose sum is σ = 21181800. Its totient is φ = 21181798.

The previous prime is 21181777. The next prime is 21181801. The reversal of 21181799 is 99718112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21181799 - 2¹² = 21177703 is a prime.

Together with 21181801, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21181729) 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, 10590899 + 10590900.

It is an arithmetic number, because the mean of its divisors is an integer number (10590900).

Almost surely, 2^21181799 is an apocalyptic number.

21181799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21181799 is an equidigital number, since it uses as much as digits as its factorization.

21181799 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 38.

The square root of 21181799 is about 4602.3688465832. The cubic root of 21181799 is about 276.6862735093.

The spelling of 21181799 in words is "twenty-one million, one hundred eighty-one thousand, seven hundred ninety-nine".