21819398 has 8 divisors (see below), whose sum is σ = 34654392. Its totient is φ = 10267936.

The previous prime is 21819383. The next prime is 21819403. The reversal of 21819398 is 89391812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21819398² = 952172258164808, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 320840 + ... + 320907.

It is an arithmetic number, because the mean of its divisors is an integer number (4331799).

Almost surely, 2^21819398 is an apocalyptic number.

21819398 is a deficient number, since it is larger than the sum of its proper divisors (12834994).

21819398 is a wasteful number, since it uses less digits than its factorization.

21819398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 641766.

The product of its digits is 31104, while the sum is 41.

The square root of 21819398 is about 4671.1238476410. The cubic root of 21819398 is about 279.4350769743.

The spelling of 21819398 in words is "twenty-one million, eight hundred nineteen thousand, three hundred ninety-eight".