21339943 has 2 divisors, whose sum is σ = 21339944. Its totient is φ = 21339942.

The previous prime is 21339931. The next prime is 21339961. The reversal of 21339943 is 34993312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21339943 - 2¹⁷ = 21208871 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21339899 and 21339908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21399943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10669971 + 10669972.

It is an arithmetic number, because the mean of its divisors is an integer number (10669972).

Almost surely, 2^21339943 is an apocalyptic number.

21339943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21339943 is an equidigital number, since it uses as much as digits as its factorization.

21339943 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 34.

The square root of 21339943 is about 4619.5176155092. The cubic root of 21339943 is about 277.3731498258.

The spelling of 21339943 in words is "twenty-one million, three hundred thirty-nine thousand, nine hundred forty-three".