205613021 has 4 divisors (see below), whose sum is σ = 205714752. Its totient is φ = 205511292.

The previous prime is 205612999. The next prime is 205613047. The reversal of 205613021 is 120316502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120316502 = 2 ⋅60158251.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-205613021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 205612984 and 205613002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205613071) 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, 47771 + ... + 51896.

It is an arithmetic number, because the mean of its divisors is an integer number (51428688).

Almost surely, 2^205613021 is an apocalyptic number.

It is an amenable number.

205613021 is a deficient number, since it is larger than the sum of its proper divisors (101731).

205613021 is an equidigital number, since it uses as much as digits as its factorization.

205613021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101730.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 205613021 is about 14339.2127050267. The cubic root of 205613021 is about 590.2240085899.

Adding to 205613021 its reverse (120316502), we get a palindrome (325929523).

The spelling of 205613021 in words is "two hundred five million, six hundred thirteen thousand, twenty-one".