21339649 has 2 divisors, whose sum is σ = 21339650. Its totient is φ = 21339648.

The previous prime is 21339629. The next prime is 21339671. The reversal of 21339649 is 94693312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19360000 + 1979649 = 4400^2 + 1407^2 .

It is a cyclic number.

It is not a de Polignac number, because 21339649 - 2¹⁵ = 21306881 is a prime.

It is not a weakly prime, because it can be changed into another prime (21339629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10669824 + 10669825.

It is an arithmetic number, because the mean of its divisors is an integer number (10669825).

Almost surely, 2^21339649 is an apocalyptic number.

It is an amenable number.

21339649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21339649 is an equidigital number, since it uses as much as digits as its factorization.

21339649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 37.

The square root of 21339649 is about 4619.4857938952. The cubic root of 21339649 is about 277.3718760317.

The spelling of 21339649 in words is "twenty-one million, three hundred thirty-nine thousand, six hundred forty-nine".