21198138 has 16 divisors (see below), whose sum is σ = 45657696. Its totient is φ = 6522480.

The previous prime is 21198137. The next prime is 21198139. The reversal of 21198138 is 83189112.

It is an interprime number because it is at equal distance from previous prime (21198137) and next prime (21198139).

It is a super-2 number, since 2×21198138² = 898722109334088, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21198099 and 21198108.

It is not an unprimeable number, because it can be changed into a prime (21198137) 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, 135808 + ... + 135963.

It is an arithmetic number, because the mean of its divisors is an integer number (2853606).

Almost surely, 2^21198138 is an apocalyptic number.

21198138 is an abundant number, since it is smaller than the sum of its proper divisors (24459558).

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

21198138 is a wasteful number, since it uses less digits than its factorization.

21198138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271789.

The product of its digits is 3456, while the sum is 33.

The square root of 21198138 is about 4604.1435685695. The cubic root of 21198138 is about 276.7573977029.

The spelling of 21198138 in words is "twenty-one million, one hundred ninety-eight thousand, one hundred thirty-eight".