204138551 has 4 divisors (see below), whose sum is σ = 204952104. Its totient is φ = 203325000.

The previous prime is 204138463. The next prime is 204138577. The reversal of 204138551 is 155831402.

204138551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-204138551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204108551) 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, 406400 + ... + 406901.

It is an arithmetic number, because the mean of its divisors is an integer number (51238026).

Almost surely, 2^204138551 is an apocalyptic number.

204138551 is a deficient number, since it is larger than the sum of its proper divisors (813553).

204138551 is an equidigital number, since it uses as much as digits as its factorization.

204138551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 813552.

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 204138551 is about 14287.7062889744. The cubic root of 204138551 is about 588.8097723163.

Adding to 204138551 its reverse (155831402), we get a palindrome (359969953).

The spelling of 204138551 in words is "two hundred four million, one hundred thirty-eight thousand, five hundred fifty-one".