20665720 has 16 divisors (see below), whose sum is σ = 46497960. Its totient is φ = 8266272.

The previous prime is 20665669. The next prime is 20665739. The reversal of 20665720 is 2756602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 258282 + ... + 258361.

Almost surely, 2^20665720 is an apocalyptic number.

20665720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20665720 is an abundant number, since it is smaller than the sum of its proper divisors (25832240).

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

20665720 is a wasteful number, since it uses less digits than its factorization.

20665720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516654 (or 516650 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 20665720 is about 4545.9564450179. The cubic root of 20665720 is about 274.4206868157.

The spelling of 20665720 in words is "twenty million, six hundred sixty-five thousand, seven hundred twenty".