20728140 has 48 divisors (see below), whose sum is σ = 59613792. Its totient is φ = 5377536.

The previous prime is 20728139. The next prime is 20728153. The reversal of 20728140 is 4182702.

It is a self number, because there is not a number n which added to its sum of digits gives 20728140.

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, 2449 + ... + 6888.

It is an arithmetic number, because the mean of its divisors is an integer number (1241954).

Almost surely, 2^20728140 is an apocalyptic number.

20728140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20728140 is an abundant number, since it is smaller than the sum of its proper divisors (38885652).

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

20728140 is a wasteful number, since it uses less digits than its factorization.

20728140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9386 (or 9384 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 20728140 is about 4552.8167105650. The cubic root of 20728140 is about 274.6967014265.

The spelling of 20728140 in words is "twenty million, seven hundred twenty-eight thousand, one hundred forty".