21954839 has 4 divisors (see below), whose sum is σ = 21964224. Its totient is φ = 21945456.

The previous prime is 21954809. The next prime is 21954841. The reversal of 21954839 is 93845912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21954839 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21954796 and 21954805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21954809) 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, 1979 + ... + 6915.

It is an arithmetic number, because the mean of its divisors is an integer number (5491056).

Almost surely, 2^21954839 is an apocalyptic number.

21954839 is a deficient number, since it is larger than the sum of its proper divisors (9385).

21954839 is an equidigital number, since it uses as much as digits as its factorization.

21954839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9384.

The product of its digits is 77760, while the sum is 41.

The square root of 21954839 is about 4685.5991079050. The cubic root of 21954839 is about 280.0120700579.

The spelling of 21954839 in words is "twenty-one million, nine hundred fifty-four thousand, eight hundred thirty-nine".