20643849 has 8 divisors (see below), whose sum is σ = 30583520. Its totient is φ = 13762548.

The previous prime is 20643809. The next prime is 20643851. The reversal of 20643849 is 94834602.

It is a happy number.

20643849 is a `hidden beast` number, since 2 + 0 + 643 + 8 + 4 + 9 = 666.

It is not a de Polignac number, because 20643849 - 2²⁰ = 19595273 is a prime.

It is a Duffinian number.

It is a zygodrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (20643809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 382267 + ... + 382320.

It is an arithmetic number, because the mean of its divisors is an integer number (3822940).

Almost surely, 2^20643849 is an apocalyptic number.

It is an amenable number.

20643849 is a deficient number, since it is larger than the sum of its proper divisors (9939671).

20643849 is an equidigital number, since it uses as much as digits as its factorization.

20643849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 764596 (or 764590 counting only the distinct ones).

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

The square root of 20643849 is about 4543.5502638355. The cubic root of 20643849 is about 274.3238440993.

The spelling of 20643849 in words is "twenty million, six hundred forty-three thousand, eight hundred forty-nine".