20643397 has 8 divisors (see below), whose sum is σ = 22042944. Its totient is φ = 19285728.

The previous prime is 20643379. The next prime is 20643407. The reversal of 20643397 is 79334602.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20643397 - 2⁷ = 20643269 is a prime.

It is a super-2 number, since 2×20643397² = 852299679399218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20643347) 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, 9448 + ... + 11425.

It is an arithmetic number, because the mean of its divisors is an integer number (2755368).

Almost surely, 2^20643397 is an apocalyptic number.

It is an amenable number.

20643397 is a deficient number, since it is larger than the sum of its proper divisors (1399547).

20643397 is a wasteful number, since it uses less digits than its factorization.

20643397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20939.

The product of its (nonzero) digits is 27216, while the sum is 34.

The square root of 20643397 is about 4543.5005227247. The cubic root of 20643397 is about 274.3218419648.

Adding to 20643397 its reverse (79334602), we get a palindrome (99977999).

The spelling of 20643397 in words is "twenty million, six hundred forty-three thousand, three hundred ninety-seven".