21919839 has 4 divisors (see below), whose sum is σ = 29226456. Its totient is φ = 14613224.

The previous prime is 21919831. The next prime is 21919847. The reversal of 21919839 is 93891912.

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

It is an interprime number because it is at equal distance from previous prime (21919831) and next prime (21919847).

It is a cyclic number.

It is not a de Polignac number, because 21919839 - 2³ = 21919831 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21919839.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21919831) 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, 3653304 + ... + 3653309.

It is an arithmetic number, because the mean of its divisors is an integer number (7306614).

Almost surely, 2^21919839 is an apocalyptic number.

21919839 is a deficient number, since it is larger than the sum of its proper divisors (7306617).

21919839 is an equidigital number, since it uses as much as digits as its factorization.

21919839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7306616.

The product of its digits is 34992, while the sum is 42.

The square root of 21919839 is about 4681.8627703084. The cubic root of 21919839 is about 279.8631942231.

The spelling of 21919839 in words is "twenty-one million, nine hundred nineteen thousand, eight hundred thirty-nine".