20728541 has 4 divisors (see below), whose sum is σ = 20852832. Its totient is φ = 20604252.

The previous prime is 20728531. The next prime is 20728549. The reversal of 20728541 is 14582702.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20728541 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20728549) 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, 61895 + ... + 62228.

It is an arithmetic number, because the mean of its divisors is an integer number (5213208).

Almost surely, 2^20728541 is an apocalyptic number.

It is an amenable number.

20728541 is a deficient number, since it is larger than the sum of its proper divisors (124291).

20728541 is a wasteful number, since it uses less digits than its factorization.

20728541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124290.

The product of its (nonzero) digits is 4480, while the sum is 29.

The square root of 20728541 is about 4552.8607490236. The cubic root of 20728541 is about 274.6984728134.

The spelling of 20728541 in words is "twenty million, seven hundred twenty-eight thousand, five hundred forty-one".