20123647 has 4 divisors (see below), whose sum is σ = 20198176. Its totient is φ = 20049120.

The previous prime is 20123633. The next prime is 20123659. The reversal of 20123647 is 74632102.

It is a Cunningham number, because it is equal to 272³-1.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20123647 - 2¹⁵ = 20090879 is a prime.

It is a super-2 number, since 2×20123647² = 809922337161218, 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 (20123617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36858 + ... + 37399.

It is an arithmetic number, because the mean of its divisors is an integer number (5049544).

Almost surely, 2^20123647 is an apocalyptic number.

20123647 is a deficient number, since it is larger than the sum of its proper divisors (74529).

20123647 is an equidigital number, since it uses as much as digits as its factorization.

20123647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74528.

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 20123647 is about 4485.9388092126. The cubic root of 20123647 is about 271.9999954945. Note that the first 5 decimals are identical.

Adding to 20123647 its reverse (74632102), we get a palindrome (94755749).

The spelling of 20123647 in words is "twenty million, one hundred twenty-three thousand, six hundred forty-seven".