20643357 has 24 divisors (see below), whose sum is σ = 32191776. Its totient is φ = 11732448.

The previous prime is 20643353. The next prime is 20643379. The reversal of 20643357 is 75334602.

It is not a de Polignac number, because 20643357 - 2² = 20643353 is a prime.

It is a super-2 number, since 2×20643357² = 852296376458898, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20643353) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 46378 + ... + 46820.

It is an arithmetic number, because the mean of its divisors is an integer number (1341324).

Almost surely, 2^20643357 is an apocalyptic number.

It is an amenable number.

20643357 is a deficient number, since it is larger than the sum of its proper divisors (11548419).

20643357 is a wasteful number, since it uses less digits than its factorization.

20643357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777 (or 770 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 30.

The square root of 20643357 is about 4543.4961208303. The cubic root of 20643357 is about 274.3216647834.

Adding to 20643357 its reverse (75334602), we get a palindrome (95977959).

The spelling of 20643357 in words is "twenty million, six hundred forty-three thousand, three hundred fifty-seven".