20728937 has 4 divisors (see below), whose sum is σ = 20934276. Its totient is φ = 20523600.

The previous prime is 20728921. The next prime is 20728949. The reversal of 20728937 is 73982702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14891881 + 5837056 = 3859^2 + 2416^2 .

It is a cyclic number.

It is not a de Polignac number, because 20728937 - 2⁴ = 20728921 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20728937.

It is not an unprimeable number, because it can be changed into a prime (20728907) 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, 102518 + ... + 102719.

It is an arithmetic number, because the mean of its divisors is an integer number (5233569).

Almost surely, 2^20728937 is an apocalyptic number.

It is an amenable number.

20728937 is a deficient number, since it is larger than the sum of its proper divisors (205339).

20728937 is a wasteful number, since it uses less digits than its factorization.

20728937 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205338.

The product of its (nonzero) digits is 42336, while the sum is 38.

The square root of 20728937 is about 4552.9042379563. The cubic root of 20728937 is about 274.7002220907.

The spelling of 20728937 in words is "twenty million, seven hundred twenty-eight thousand, nine hundred thirty-seven".