21198418 has 4 divisors (see below), whose sum is σ = 31797630. Its totient is φ = 10599208.

The previous prime is 21198409. The next prime is 21198427. The reversal of 21198418 is 81489112.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21198409) and next prime (21198427).

It can be written as a sum of positive squares in only one way, i.e., 14265729 + 6932689 = 3777^2 + 2633^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5299603 + ... + 5299606.

Almost surely, 2^21198418 is an apocalyptic number.

21198418 is a deficient number, since it is larger than the sum of its proper divisors (10599212).

21198418 is a wasteful number, since it uses less digits than its factorization.

21198418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10599211.

The product of its digits is 4608, while the sum is 34.

The square root of 21198418 is about 4604.1739758615. The cubic root of 21198418 is about 276.7586162334.

The spelling of 21198418 in words is "twenty-one million, one hundred ninety-eight thousand, four hundred eighteen".