20712145 has 4 divisors (see below), whose sum is σ = 24854580. Its totient is φ = 16569712.

The previous prime is 20712143. The next prime is 20712151. The reversal of 20712145 is 54121702.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54121702 = 2 ⋅27060851.

It can be written as a sum of positive squares in 2 ways, for example, as 12623809 + 8088336 = 3553^2 + 2844^2 .

It is a cyclic number.

It is not a de Polignac number, because 20712145 - 2¹ = 20712143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20712143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2071210 + ... + 2071219.

It is an arithmetic number, because the mean of its divisors is an integer number (6213645).

Almost surely, 2^20712145 is an apocalyptic number.

It is an amenable number.

20712145 is a deficient number, since it is larger than the sum of its proper divisors (4142435).

20712145 is an equidigital number, since it uses as much as digits as its factorization.

20712145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4142434.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 20712145 is about 4551.0597666917. The cubic root of 20712145 is about 274.6260260968.

Adding to 20712145 its reverse (54121702), we get a palindrome (74833847).

The spelling of 20712145 in words is "twenty million, seven hundred twelve thousand, one hundred forty-five".