20640736 has 12 divisors (see below), whose sum is σ = 40636512. Its totient is φ = 10320352.

The previous prime is 20640733. The next prime is 20640751. The reversal of 20640736 is 63704602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322480 + ... + 322543.

It is an arithmetic number, because the mean of its divisors is an integer number (3386376).

Almost surely, 2^20640736 is an apocalyptic number.

It is an amenable number.

20640736 is a deficient number, since it is larger than the sum of its proper divisors (19995776).

20640736 is an equidigital number, since it uses as much as digits as its factorization.

20640736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 645033 (or 645025 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 28.

The square root of 20640736 is about 4543.2076774015. The cubic root of 20640736 is about 274.3100544703.

The spelling of 20640736 in words is "twenty million, six hundred forty thousand, seven hundred thirty-six".