21438398 has 4 divisors (see below), whose sum is σ = 32157600. Its totient is φ = 10719198.

The previous prime is 21438359. The next prime is 21438401. The reversal of 21438398 is 89383412.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5359598 + ... + 5359601.

It is an arithmetic number, because the mean of its divisors is an integer number (8039400).

Almost surely, 2^21438398 is an apocalyptic number.

21438398 is a deficient number, since it is larger than the sum of its proper divisors (10719202).

21438398 is a wasteful number, since it uses less digits than its factorization.

21438398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10719201.

The product of its digits is 41472, while the sum is 38.

The square root of 21438398 is about 4630.1617682323. The cubic root of 21438398 is about 277.7990629141.

The spelling of 21438398 in words is "twenty-one million, four hundred thirty-eight thousand, three hundred ninety-eight".