20781842 has 16 divisors (see below), whose sum is σ = 32638464. Its totient is φ = 9912000.

The previous prime is 20781841. The next prime is 20781851. The reversal of 20781842 is 24818702.

It is a junction number, because it is equal to n+sod(n) for n = 20781799 and 20781808.

It is not an unprimeable number, because it can be changed into a prime (20781841) 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, 2042 + ... + 6762.

It is an arithmetic number, because the mean of its divisors is an integer number (2039904).

Almost surely, 2^20781842 is an apocalyptic number.

20781842 is a deficient number, since it is larger than the sum of its proper divisors (11856622).

20781842 is a wasteful number, since it uses less digits than its factorization.

20781842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4825.

The product of its (nonzero) digits is 7168, while the sum is 32.

The square root of 20781842 is about 4558.7105633063. The cubic root of 20781842 is about 274.9337228710.

The spelling of 20781842 in words is "twenty million, seven hundred eighty-one thousand, eight hundred forty-two".