21395998 has 16 divisors (see below), whose sum is σ = 35300160. Its totient is φ = 9664416.

The previous prime is 21395987. The next prime is 21395999. The reversal of 21395998 is 89959312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21395999) 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 in 7 ways as a sum of consecutive naturals, for example, 7533 + ... + 9976.

It is an arithmetic number, because the mean of its divisors is an integer number (2206260).

Almost surely, 2^21395998 is an apocalyptic number.

21395998 is a deficient number, since it is larger than the sum of its proper divisors (13904162).

21395998 is a wasteful number, since it uses less digits than its factorization.

21395998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17571.

The product of its digits is 174960, while the sum is 46.

The square root of 21395998 is about 4625.5808283933. The cubic root of 21395998 is about 277.6158021135.

The spelling of 21395998 in words is "twenty-one million, three hundred ninety-five thousand, nine hundred ninety-eight".