20781872 has 20 divisors (see below), whose sum is σ = 40752600. Its totient is φ = 10265088.

The previous prime is 20781863. The next prime is 20781889. The reversal of 20781872 is 27818702.

It is a zygodrome in base 3.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6497 + ... + 9152.

It is an arithmetic number, because the mean of its divisors is an integer number (2037630).

Almost surely, 2^20781872 is an apocalyptic number.

It is an amenable number.

20781872 is a deficient number, since it is larger than the sum of its proper divisors (19970728).

20781872 is a wasteful number, since it uses less digits than its factorization.

20781872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15740 (or 15734 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 35.

The square root of 20781872 is about 4558.7138537092. The cubic root of 20781872 is about 274.9338551661.

The spelling of 20781872 in words is "twenty million, seven hundred eighty-one thousand, eight hundred seventy-two".