20651680 has 48 divisors (see below), whose sum is σ = 55762560. Its totient is φ = 7080192.

The previous prime is 20651641. The next prime is 20651681. The reversal of 20651680 is 8615602.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (20651681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8100 + ... + 10339.

It is an arithmetic number, because the mean of its divisors is an integer number (1161720).

Almost surely, 2^20651680 is an apocalyptic number.

20651680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20651680 is an abundant number, since it is smaller than the sum of its proper divisors (35110880).

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

20651680 is a wasteful number, since it uses less digits than its factorization.

20651680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18461 (or 18453 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 20651680 is about 4544.4119531574. The cubic root of 20651680 is about 274.3585268829.

The spelling of 20651680 in words is "twenty million, six hundred fifty-one thousand, six hundred eighty".