20643249 has 16 divisors (see below), whose sum is σ = 30340800. Its totient is φ = 12380160.

The previous prime is 20643239. The next prime is 20643251. The reversal of 20643249 is 94234602.

It is not a de Polignac number, because 20643249 - 2²¹ = 18546097 is a prime.

It is a super-3 number, since 3×20643249³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (20643229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24 + ... + 6425.

It is an arithmetic number, because the mean of its divisors is an integer number (1896300).

Almost surely, 2^20643249 is an apocalyptic number.

It is an amenable number.

20643249 is a deficient number, since it is larger than the sum of its proper divisors (9697551).

20643249 is a wasteful number, since it uses less digits than its factorization.

20643249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6560.

The product of its (nonzero) digits is 10368, while the sum is 30.

The square root of 20643249 is about 4543.4842356940. The cubic root of 20643249 is about 274.3211863923.

The spelling of 20643249 in words is "twenty million, six hundred forty-three thousand, two hundred forty-nine".