20728897 has 4 divisors (see below), whose sum is σ = 23690176. Its totient is φ = 17767620.

The previous prime is 20728891. The next prime is 20728907. The reversal of 20728897 is 79882702.

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-20728897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20728891) 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, 1480629 + ... + 1480642.

It is an arithmetic number, because the mean of its divisors is an integer number (5922544).

Almost surely, 2^20728897 is an apocalyptic number.

It is an amenable number.

20728897 is a deficient number, since it is larger than the sum of its proper divisors (2961279).

20728897 is an equidigital number, since it uses as much as digits as its factorization.

20728897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2961278.

The product of its (nonzero) digits is 112896, while the sum is 43.

The square root of 20728897 is about 4552.8998451536. The cubic root of 20728897 is about 274.7000453971.

The spelling of 20728897 in words is "twenty million, seven hundred twenty-eight thousand, eight hundred ninety-seven".