20728019 has 6 divisors (see below), whose sum is σ = 22445316. Its totient is φ = 19133400.

The previous prime is 20728009. The next prime is 20728033. The reversal of 20728019 is 91082702.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-20728019 is a prime.

It is a super-2 number, since 2×20728019² = 859301543328722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20727982 and 20728000.

It is not an unprimeable number, because it can be changed into a prime (20728009) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 61157 + ... + 61494.

It is an arithmetic number, because the mean of its divisors is an integer number (3740886).

Almost surely, 2^20728019 is an apocalyptic number.

20728019 is a deficient number, since it is larger than the sum of its proper divisors (1717297).

20728019 is a wasteful number, since it uses less digits than its factorization.

20728019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122677 (or 122664 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 20728019 is about 4552.8034220686. The cubic root of 20728019 is about 274.6961669137.

The spelling of 20728019 in words is "twenty million, seven hundred twenty-eight thousand, nineteen".