20640236 has 12 divisors (see below), whose sum is σ = 36165528. Its totient is φ = 10307232.

The previous prime is 20640233. The next prime is 20640247. The reversal of 20640236 is 63204602.

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 3 ways as a sum of consecutive naturals, for example, 995 + ... + 6501.

It is an arithmetic number, because the mean of its divisors is an integer number (3013794).

Almost surely, 2^20640236 is an apocalyptic number.

It is an amenable number.

20640236 is a deficient number, since it is larger than the sum of its proper divisors (15525292).

20640236 is a wasteful number, since it uses less digits than its factorization.

20640236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6448 (or 6446 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 20640236 is about 4543.1526498677. The cubic root of 20640236 is about 274.3078394954.

Adding to 20640236 its reverse (63204602), we get a palindrome (83844838).

The spelling of 20640236 in words is "twenty million, six hundred forty thousand, two hundred thirty-six".