205143921 has 20 divisors (see below), whose sum is σ = 310774464. Its totient is φ = 134832600.

The previous prime is 205143907. The next prime is 205143959. The reversal of 205143921 is 129341502.

205143921 is a `hidden beast` number, since 205 + 1 + 439 + 21 = 666.

It is not a de Polignac number, because 205143921 - 2⁶ = 205143857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205143901) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 12085 + ... + 23586.

Almost surely, 2^205143921 is an apocalyptic number.

It is an amenable number.

205143921 is a deficient number, since it is larger than the sum of its proper divisors (105630543).

205143921 is an equidigital number, since it uses as much as digits as its factorization.

205143921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35754 (or 35745 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 205143921 is about 14322.8461207960. The cubic root of 205143921 is about 589.7748072887.

The spelling of 205143921 in words is "two hundred five million, one hundred forty-three thousand, nine hundred twenty-one".