21843979 has 2 divisors, whose sum is σ = 21843980. Its totient is φ = 21843978.

The previous prime is 21843953. The next prime is 21844001. The reversal of 21843979 is 97934812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21843979 - 2⁷ = 21843851 is a prime.

It is not a weakly prime, because it can be changed into another prime (21843919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10921989 + 10921990.

It is an arithmetic number, because the mean of its divisors is an integer number (10921990).

Almost surely, 2^21843979 is an apocalyptic number.

21843979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21843979 is an equidigital number, since it uses as much as digits as its factorization.

21843979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 43.

The square root of 21843979 is about 4673.7542725308. The cubic root of 21843979 is about 279.5399716473.

It can be divided in two parts, 21843 and 979, that added together give a palindrome (22822).

The spelling of 21843979 in words is "twenty-one million, eight hundred forty-three thousand, nine hundred seventy-nine".