21819401 has 4 divisors (see below), whose sum is σ = 21836100. Its totient is φ = 21802704.

The previous prime is 21819383. The next prime is 21819403. The reversal of 21819401 is 10491812.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5017600 + 16801801 = 2240^2 + 4099^2 .

It is a cyclic number.

It is not a de Polignac number, because 21819401 - 2⁶ = 21819337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21819403) 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, 6206 + ... + 9063.

It is an arithmetic number, because the mean of its divisors is an integer number (5459025).

Almost surely, 2^21819401 is an apocalyptic number.

It is an amenable number.

21819401 is a deficient number, since it is larger than the sum of its proper divisors (16699).

21819401 is a wasteful number, since it uses less digits than its factorization.

21819401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16698.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 21819401 is about 4671.1241687628. The cubic root of 21819401 is about 279.4350897810.

The spelling of 21819401 in words is "twenty-one million, eight hundred nineteen thousand, four hundred one".