20640727 has 4 divisors (see below), whose sum is σ = 20853616. Its totient is φ = 20427840.

The previous prime is 20640713. The next prime is 20640733. The reversal of 20640727 is 72704602.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20640727 is a prime.

It is a super-2 number, since 2×20640727² = 852079222177058, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20640695 and 20640704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640787) 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, 106299 + ... + 106492.

It is an arithmetic number, because the mean of its divisors is an integer number (5213404).

Almost surely, 2^20640727 is an apocalyptic number.

20640727 is a deficient number, since it is larger than the sum of its proper divisors (212889).

20640727 is an equidigital number, since it uses as much as digits as its factorization.

20640727 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212888.

The product of its (nonzero) digits is 4704, while the sum is 28.

The square root of 20640727 is about 4543.2066869118. The cubic root of 20640727 is about 274.3100146010.

The spelling of 20640727 in words is "twenty million, six hundred forty thousand, seven hundred twenty-seven".