21843649 has 2 divisors, whose sum is σ = 21843650. Its totient is φ = 21843648.

The previous prime is 21843643. The next prime is 21843659. The reversal of 21843649 is 94634812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15249025 + 6594624 = 3905^2 + 2568^2 .

It is a cyclic number.

It is not a de Polignac number, because 21843649 - 2⁵ = 21843617 is a prime.

It is not a weakly prime, because it can be changed into another prime (21843643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10921824 + 10921825.

It is an arithmetic number, because the mean of its divisors is an integer number (10921825).

Almost surely, 2^21843649 is an apocalyptic number.

It is an amenable number.

21843649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21843649 is an equidigital number, since it uses as much as digits as its factorization.

21843649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 37.

The square root of 21843649 is about 4673.7189688726. The cubic root of 21843649 is about 279.5385639572.

The spelling of 21843649 in words is "twenty-one million, eight hundred forty-three thousand, six hundred forty-nine".