21018799 has 2 divisors, whose sum is σ = 21018800. Its totient is φ = 21018798.

The previous prime is 21018779. The next prime is 21018821. The reversal of 21018799 is 99781012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21018799 - 2⁹ = 21018287 is a prime.

It is a super-2 number, since 2×21018799² = 883579822804802, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21018719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509399 + 10509400.

It is an arithmetic number, because the mean of its divisors is an integer number (10509400).

Almost surely, 2^21018799 is an apocalyptic number.

21018799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21018799 is an equidigital number, since it uses as much as digits as its factorization.

21018799 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 21018799 is about 4584.6263751804. The cubic root of 21018799 is about 275.9747185063.

The spelling of 21018799 in words is "twenty-one million, eighteen thousand, seven hundred ninety-nine".