20561145 has 32 divisors (see below), whose sum is σ = 37134720. Its totient is φ = 9623040.

The previous prime is 20561117. The next prime is 20561147. The reversal of 20561145 is 54116502.

It is not a de Polignac number, because 20561145 - 2⁵ = 20561113 is a prime.

It is a super-2 number, since 2×20561145² = 845521367422050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20561147) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2637 + ... + 6933.

It is an arithmetic number, because the mean of its divisors is an integer number (1160460).

Almost surely, 2^20561145 is an apocalyptic number.

It is an amenable number.

20561145 is a deficient number, since it is larger than the sum of its proper divisors (16573575).

20561145 is a wasteful number, since it uses less digits than its factorization.

20561145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4345.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 20561145 is about 4534.4398772064. The cubic root of 20561145 is about 273.9570190276.

Adding to 20561145 its reverse (54116502), we get a palindrome (74677647).

It can be divided in two parts, 20561 and 145, that added together give a triangular number (20706 = T₂₀₃).

The spelling of 20561145 in words is "twenty million, five hundred sixty-one thousand, one hundred forty-five".