20728742 has 8 divisors (see below), whose sum is σ = 31233216. Its totient is φ = 10317672.

The previous prime is 20728733. The next prime is 20728759. The reversal of 20728742 is 24782702.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 20728699 and 20728708.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22793 + ... + 23684.

It is an arithmetic number, because the mean of its divisors is an integer number (3904152).

Almost surely, 2^20728742 is an apocalyptic number.

20728742 is a deficient number, since it is larger than the sum of its proper divisors (10504474).

20728742 is a wasteful number, since it uses less digits than its factorization.

20728742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46702.

The product of its (nonzero) digits is 12544, while the sum is 32.

The square root of 20728742 is about 4552.8828230035. The cubic root of 20728742 is about 274.6993607069.

The spelling of 20728742 in words is "twenty million, seven hundred twenty-eight thousand, seven hundred forty-two".