20640235 has 16 divisors (see below), whose sum is σ = 30880512. Its totient is φ = 12866400.

The previous prime is 20640233. The next prime is 20640247. The reversal of 20640235 is 53204602.

It is a happy number.

It is not a de Polignac number, because 20640235 - 2¹ = 20640233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20640233) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26421 + ... + 27190.

It is an arithmetic number, because the mean of its divisors is an integer number (1930032).

Almost surely, 2^20640235 is an apocalyptic number.

20640235 is a deficient number, since it is larger than the sum of its proper divisors (10240277).

20640235 is a wasteful number, since it uses less digits than its factorization.

20640235 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53634.

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 20640235 is about 4543.1525398120. The cubic root of 20640235 is about 274.3078350654.

Adding to 20640235 its reverse (53204602), we get a palindrome (73844837).

The spelling of 20640235 in words is "twenty million, six hundred forty thousand, two hundred thirty-five".