21105619 has 4 divisors (see below), whose sum is σ = 22347144. Its totient is φ = 19864096.

The previous prime is 21105587. The next prime is 21105641. The reversal of 21105619 is 91650112.

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

It is a cyclic number.

It is not a de Polignac number, because 21105619 - 2⁵ = 21105587 is a prime.

It is a super-2 number, since 2×21105619² = 890894306746322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21105593 and 21105602.

It is not an unprimeable number, because it can be changed into a prime (21105659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 620737 + ... + 620770.

It is an arithmetic number, because the mean of its divisors is an integer number (5586786).

Almost surely, 2^21105619 is an apocalyptic number.

21105619 is a deficient number, since it is larger than the sum of its proper divisors (1241525).

21105619 is a wasteful number, since it uses less digits than its factorization.

21105619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1241524.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 21105619 is about 4594.0852190616. The cubic root of 21105619 is about 276.3541758158.

The spelling of 21105619 in words is "twenty-one million, one hundred five thousand, six hundred nineteen".