20640490 has 32 divisors (see below), whose sum is σ = 40279680. Its totient is φ = 7569984.

The previous prime is 20640469. The next prime is 20640493. The reversal of 20640490 is 9404602.

It is not an unprimeable number, because it can be changed into a prime (20640493) 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, 22827 + ... + 23713.

It is an arithmetic number, because the mean of its divisors is an integer number (1258740).

Almost surely, 2^20640490 is an apocalyptic number.

20640490 is a deficient number, since it is larger than the sum of its proper divisors (19639190).

20640490 is a wasteful number, since it uses less digits than its factorization.

20640490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1086.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 20640490 is about 4543.1806039382. The cubic root of 20640490 is about 274.3089647071.

The spelling of 20640490 in words is "twenty million, six hundred forty thousand, four hundred ninety".