20728837 has 4 divisors (see below), whose sum is σ = 21068716. Its totient is φ = 20388960.

The previous prime is 20728817. The next prime is 20728847. The reversal of 20728837 is 73882702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5354596 + 15374241 = 2314^2 + 3921^2 .

It is a cyclic number.

It is not a de Polignac number, because 20728837 - 2¹¹ = 20726789 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20728796 and 20728805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20728817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 169848 + ... + 169969.

It is an arithmetic number, because the mean of its divisors is an integer number (5267179).

Almost surely, 2^20728837 is an apocalyptic number.

It is an amenable number.

20728837 is a deficient number, since it is larger than the sum of its proper divisors (339879).

20728837 is an equidigital number, since it uses as much as digits as its factorization.

20728837 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 339878.

The product of its (nonzero) digits is 37632, while the sum is 37.

The square root of 20728837 is about 4552.8932559418. The cubic root of 20728837 is about 274.6997803561.

The spelling of 20728837 in words is "twenty million, seven hundred twenty-eight thousand, eight hundred thirty-seven".