21339499 has 2 divisors, whose sum is σ = 21339500. Its totient is φ = 21339498.

The previous prime is 21339497. The next prime is 21339503. The reversal of 21339499 is 99493312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21339499 - 2¹ = 21339497 is a prime.

Together with 21339497, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21339497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10669749 + 10669750.

It is an arithmetic number, because the mean of its divisors is an integer number (10669750).

Almost surely, 2^21339499 is an apocalyptic number.

21339499 is a deficient number, since it is larger than the sum of its proper divisors (1).

21339499 is an equidigital number, since it uses as much as digits as its factorization.

21339499 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52488, while the sum is 40.

The square root of 21339499 is about 4619.4695582935. The cubic root of 21339499 is about 277.3712261322.

The spelling of 21339499 in words is "twenty-one million, three hundred thirty-nine thousand, four hundred ninety-nine".