20731745 has 8 divisors (see below), whose sum is σ = 25347816. Its totient is φ = 16272256.

The previous prime is 20731741. The next prime is 20731757. The reversal of 20731745 is 54713702.

It can be written as a sum of positive squares in 4 ways, for example, as 192721 + 20539024 = 439^2 + 4532^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20731745 - 2² = 20731741 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20731741) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 38852 + ... + 39381.

It is an arithmetic number, because the mean of its divisors is an integer number (3168477).

Almost surely, 2^20731745 is an apocalyptic number.

It is an amenable number.

20731745 is a deficient number, since it is larger than the sum of its proper divisors (4616071).

20731745 is an equidigital number, since it uses as much as digits as its factorization.

20731745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78291.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 20731745 is about 4553.2126021085. The cubic root of 20731745 is about 274.7126254184.

The spelling of 20731745 in words is "twenty million, seven hundred thirty-one thousand, seven hundred forty-five".