21819842 has 8 divisors (see below), whose sum is σ = 35705232. Its totient is φ = 9918100.

The previous prime is 21819841. The next prime is 21819869. The reversal of 21819842 is 24891812.

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

It is a super-2 number, since 2×21819842² = 952211009809928, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21819841) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 495884 + ... + 495927.

It is an arithmetic number, because the mean of its divisors is an integer number (4463154).

Almost surely, 2^21819842 is an apocalyptic number.

21819842 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21819842 is a deficient number, since it is larger than the sum of its proper divisors (13885390).

21819842 is a wasteful number, since it uses less digits than its factorization.

21819842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991824.

The product of its digits is 9216, while the sum is 35.

The square root of 21819842 is about 4671.1713734351. The cubic root of 21819842 is about 279.4369723570.

The spelling of 21819842 in words is "twenty-one million, eight hundred nineteen thousand, eight hundred forty-two".