20640501 has 40 divisors (see below), whose sum is σ = 35893440. Its totient is φ = 11575872.

The previous prime is 20640497. The next prime is 20640511. The reversal of 20640501 is 10504602.

It is a happy number.

20640501 is a `hidden beast` number, since 20 + 640 + 5 + 0 + 1 = 666.

It is not a de Polignac number, because 20640501 - 2² = 20640497 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640511) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 33145 + ... + 33761.

It is an arithmetic number, because the mean of its divisors is an integer number (897336).

Almost surely, 2^20640501 is an apocalyptic number.

20640501 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20640501 is a deficient number, since it is larger than the sum of its proper divisors (15252939).

20640501 is an equidigital number, since it uses as much as digits as its factorization.

20640501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695 (or 686 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 20640501 is about 4543.1818145436. The cubic root of 20640501 is about 274.3090134365.

The spelling of 20640501 in words is "twenty million, six hundred forty thousand, five hundred one".