20717720 has 32 divisors (see below), whose sum is σ = 46926000. Its totient is φ = 8231808.

The previous prime is 20717717. The next prime is 20717773. The reversal of 20717720 is 2771702.

It is a self number, because there is not a number n which added to its sum of digits gives 20717720.

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, 4631 + ... + 7929.

Almost surely, 2^20717720 is an apocalyptic number.

20717720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20717720 is an abundant number, since it is smaller than the sum of its proper divisors (26208280).

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

20717720 is a wasteful number, since it uses less digits than its factorization.

20717720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3467 (or 3463 counting only the distinct ones).

The product of its (nonzero) digits is 1372, while the sum is 26.

The square root of 20717720 is about 4551.6722201846. The cubic root of 20717720 is about 274.6506638596.

The spelling of 20717720 in words is "twenty million, seven hundred seventeen thousand, seven hundred twenty".