20657680 has 80 divisors (see below), whose sum is σ = 51068160. Its totient is φ = 7755264.

The previous prime is 20657677. The next prime is 20657699. The reversal of 20657680 is 8675602.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 189466 + ... + 189574.

It is an arithmetic number, because the mean of its divisors is an integer number (638352).

Almost surely, 2^20657680 is an apocalyptic number.

20657680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20657680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25534080).

20657680 is an abundant number, since it is smaller than the sum of its proper divisors (30410480).

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

20657680 is a wasteful number, since it uses less digits than its factorization.

20657680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248 (or 242 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 20657680 is about 4545.0720566345. The cubic root of 20657680 is about 274.3850944029.

The spelling of 20657680 in words is "twenty million, six hundred fifty-seven thousand, six hundred eighty".