205521342551 has 4 divisors (see below), whose sum is σ = 234881534352. Its totient is φ = 176161150752.

The previous prime is 205521342527. The next prime is 205521342553. The reversal of 205521342551 is 155243125502.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 205521342551 - 2¹⁴ = 205521326167 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 (205521342553) 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, 14680095890 + ... + 14680095903.

It is an arithmetic number, because the mean of its divisors is an integer number (58720383588).

Almost surely, 2^205521342551 is an apocalyptic number.

205521342551 is a deficient number, since it is larger than the sum of its proper divisors (29360191801).

205521342551 is an equidigital number, since it uses as much as digits as its factorization.

205521342551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29360191800.

The product of its (nonzero) digits is 60000, while the sum is 35.

The spelling of 205521342551 in words is "two hundred five billion, five hundred twenty-one million, three hundred forty-two thousand, five hundred fifty-one".