21286398 has 32 divisors (see below), whose sum is σ = 50227200. Its totient is φ = 5885280.

The previous prime is 21286393. The next prime is 21286399. The reversal of 21286398 is 89368212.

It is a happy number.

It is a super-2 number, since 2×21286398² = 906221479628808, which contains 22 as substring.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21286393) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6873 + ... + 9476.

It is an arithmetic number, because the mean of its divisors is an integer number (1569600).

Almost surely, 2^21286398 is an apocalyptic number.

21286398 is an abundant number, since it is smaller than the sum of its proper divisors (28940802).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21286398 is a wasteful number, since it uses less digits than its factorization.

21286398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16392.

The product of its digits is 41472, while the sum is 39.

The square root of 21286398 is about 4613.7184569499. The cubic root of 21286398 is about 277.1409657544.

The spelling of 21286398 in words is "twenty-one million, two hundred eighty-six thousand, three hundred ninety-eight".