20843649 has 20 divisors (see below), whose sum is σ = 32970564. Its totient is φ = 13077504.

The previous prime is 20843629. The next prime is 20843653. The reversal of 20843649 is 94634802.

It is a happy number.

20843649 is a `hidden beast` number, since 2 + 0 + 8 + 4 + 3 + 649 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 14493249 + 6350400 = 3807^2 + 2520^2 .

It is not a de Polignac number, because 20843649 - 2⁷ = 20843521 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20843629) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6192 + ... + 8945.

Almost surely, 2^20843649 is an apocalyptic number.

It is an amenable number.

20843649 is a deficient number, since it is larger than the sum of its proper divisors (12126915).

20843649 is a wasteful number, since it uses less digits than its factorization.

20843649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15166 (or 15157 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 20843649 is about 4565.4845306933. The cubic root of 20843649 is about 275.2060120219.

The spelling of 20843649 in words is "twenty million, eight hundred forty-three thousand, six hundred forty-nine".