20640508 has 24 divisors (see below), whose sum is σ = 41385344. Its totient is φ = 8823600.

The previous prime is 20640497. The next prime is 20640511. The reversal of 20640508 is 80504602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15343 + ... + 16633.

Almost surely, 2^20640508 is an apocalyptic number.

20640508 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

20640508 is an abundant number, since it is smaller than the sum of its proper divisors (20744836).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20640508 is a wasteful number, since it uses less digits than its factorization.

20640508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1873 (or 1871 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 20640508 is about 4543.1825849288. The cubic root of 20640508 is about 274.3090444462.

The spelling of 20640508 in words is "twenty million, six hundred forty thousand, five hundred eight".