21343649 has 2 divisors, whose sum is σ = 21343650. Its totient is φ = 21343648.

The previous prime is 21343643. The next prime is 21343661. The reversal of 21343649 is 94634312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19963024 + 1380625 = 4468^2 + 1175^2 .

It is a cyclic number.

It is not a de Polignac number, because 21343649 - 2⁴ = 21343633 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21343643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10671824 + 10671825.

It is an arithmetic number, because the mean of its divisors is an integer number (10671825).

Almost surely, 2^21343649 is an apocalyptic number.

It is an amenable number.

21343649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21343649 is an equidigital number, since it uses as much as digits as its factorization.

21343649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 32.

The square root of 21343649 is about 4619.9187222288. The cubic root of 21343649 is about 277.3892055605.

The spelling of 21343649 in words is "twenty-one million, three hundred forty-three thousand, six hundred forty-nine".