20728673 has 4 divisors (see below), whose sum is σ = 23689920. Its totient is φ = 17767428.

The previous prime is 20728637. The next prime is 20728691. The reversal of 20728673 is 37682702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20728673 - 2²² = 16534369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20728633) 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, 1480613 + ... + 1480626.

It is an arithmetic number, because the mean of its divisors is an integer number (5922480).

Almost surely, 2^20728673 is an apocalyptic number.

It is an amenable number.

20728673 is a deficient number, since it is larger than the sum of its proper divisors (2961247).

20728673 is an equidigital number, since it uses as much as digits as its factorization.

20728673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2961246.

The product of its (nonzero) digits is 28224, while the sum is 35.

The square root of 20728673 is about 4552.8752453807. The cubic root of 20728673 is about 274.6990559083.

The spelling of 20728673 in words is "twenty million, seven hundred twenty-eight thousand, six hundred seventy-three".