20640641 has 8 divisors (see below), whose sum is σ = 23631744. Its totient is φ = 17660160.

The previous prime is 20640617. The next prime is 20640647. The reversal of 20640641 is 14604602.

It is a happy number.

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

It is not a de Polignac number, because 20640641 - 2⁶ = 20640577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20640647) 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 7 ways as a sum of consecutive naturals, for example, 2081 + ... + 6753.

It is an arithmetic number, because the mean of its divisors is an integer number (2953968).

Almost surely, 2^20640641 is an apocalyptic number.

It is an amenable number.

20640641 is a deficient number, since it is larger than the sum of its proper divisors (2991103).

20640641 is an equidigital number, since it uses as much as digits as its factorization.

20640641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5311.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 20640641 is about 4543.1972222214. The cubic root of 20640641 is about 274.3096336278.

The spelling of 20640641 in words is "twenty million, six hundred forty thousand, six hundred forty-one".