20648391 has 4 divisors (see below), whose sum is σ = 27531192. Its totient is φ = 13765592.

The previous prime is 20648389. The next prime is 20648401. The reversal of 20648391 is 19384602.

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 20648391 - 2¹ = 20648389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20648321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3441396 + ... + 3441401.

It is an arithmetic number, because the mean of its divisors is an integer number (6882798).

Almost surely, 2^20648391 is an apocalyptic number.

20648391 is a deficient number, since it is larger than the sum of its proper divisors (6882801).

20648391 is an equidigital number, since it uses as much as digits as its factorization.

20648391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6882800.

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 20648391 is about 4544.0500657453. The cubic root of 20648391 is about 274.3439612704.

The spelling of 20648391 in words is "twenty million, six hundred forty-eight thousand, three hundred ninety-one".