20191680 has 280 divisors, whose sum is σ = 77449680. Its totient is φ = 4976640.

The previous prime is 20191673. The next prime is 20191687. The reversal of 20191680 is 8619102.

It is an interprime number because it is at equal distance from previous prime (20191673) and next prime (20191687).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20191687) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 492460 + ... + 492500.

It is an arithmetic number, because the mean of its divisors is an integer number (276606).

Almost surely, 2^20191680 is an apocalyptic number.

20191680 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 20191680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38724840).

20191680 is an abundant number, since it is smaller than the sum of its proper divisors (57258000).

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

20191680 is a wasteful number, since it uses less digits than its factorization.

20191680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89 (or 70 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 20191680 is about 4493.5153276694. The cubic root of 20191680 is about 272.3061719580.

The spelling of 20191680 in words is "twenty million, one hundred ninety-one thousand, six hundred eighty".