21798499 has 2 divisors, whose sum is σ = 21798500. Its totient is φ = 21798498.

The previous prime is 21798467. The next prime is 21798509. The reversal of 21798499 is 99489712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21798499 - 2⁵ = 21798467 is a prime.

It is not a weakly prime, because it can be changed into another prime (21798409) 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, 10899249 + 10899250.

It is an arithmetic number, because the mean of its divisors is an integer number (10899250).

Almost surely, 2^21798499 is an apocalyptic number.

21798499 is a deficient number, since it is larger than the sum of its proper divisors (1).

21798499 is an equidigital number, since it uses as much as digits as its factorization.

21798499 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 49.

The square root of 21798499 is about 4668.8862697650. The cubic root of 21798499 is about 279.3458325446.

The spelling of 21798499 in words is "twenty-one million, seven hundred ninety-eight thousand, four hundred ninety-nine".