20406728 has 16 divisors (see below), whose sum is σ = 38377500. Its totient is φ = 10172736.

The previous prime is 20406697. The next prime is 20406767. The reversal of 20406728 is 82760402.

It can be written as a sum of positive squares in 2 ways, for example, as 20232004 + 174724 = 4498^2 + 418^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20406728.

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, 863 + ... + 6446.

Almost surely, 2^20406728 is an apocalyptic number.

It is an amenable number.

20406728 is a deficient number, since it is larger than the sum of its proper divisors (17970772).

20406728 is a wasteful number, since it uses less digits than its factorization.

20406728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7664 (or 7660 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 29.

The square root of 20406728 is about 4517.3806569737. The cubic root of 20406728 is about 273.2694767876.

The spelling of 20406728 in words is "twenty million, four hundred six thousand, seven hundred twenty-eight".