21775799 has 2 divisors, whose sum is σ = 21775800. Its totient is φ = 21775798.

The previous prime is 21775783. The next prime is 21775807. The reversal of 21775799 is 99757712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21775799 - 2⁴ = 21775783 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21775099) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10887899 + 10887900.

It is an arithmetic number, because the mean of its divisors is an integer number (10887900).

Almost surely, 2^21775799 is an apocalyptic number.

21775799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21775799 is an equidigital number, since it uses as much as digits as its factorization.

21775799 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 277830, while the sum is 47.

The square root of 21775799 is about 4666.4546499457. The cubic root of 21775799 is about 279.2488327037.

The spelling of 21775799 in words is "twenty-one million, seven hundred seventy-five thousand, seven hundred ninety-nine".