20281145 has 4 divisors (see below), whose sum is σ = 24337380. Its totient is φ = 16224912.

The previous prime is 20281141. The next prime is 20281159. The reversal of 20281145 is 54118202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54118202 = 2 ⋅27059101.

It can be written as a sum of positive squares in 2 ways, for example, as 15155449 + 5125696 = 3893^2 + 2264^2 .

It is a cyclic number.

It is not a de Polignac number, because 20281145 - 2² = 20281141 is a prime.

It is a super-2 number, since 2×20281145² = 822649685022050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20281145.

It is not an unprimeable number, because it can be changed into a prime (20281141) 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, 2028110 + ... + 2028119.

It is an arithmetic number, because the mean of its divisors is an integer number (6084345).

Almost surely, 2^20281145 is an apocalyptic number.

It is an amenable number.

20281145 is a deficient number, since it is larger than the sum of its proper divisors (4056235).

20281145 is an equidigital number, since it uses as much as digits as its factorization.

20281145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4056234.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 20281145 is about 4503.4592259729. The cubic root of 20281145 is about 272.7077561623.

Adding to 20281145 its reverse (54118202), we get a palindrome (74399347).

The spelling of 20281145 in words is "twenty million, two hundred eighty-one thousand, one hundred forty-five".