205521459021 has 12 divisors (see below), whose sum is σ = 301295141472. Its totient is φ = 134969315976.

The previous prime is 205521458983. The next prime is 205521459023. The reversal of 205521459021 is 120954125502.

205521459021 is a `hidden beast` number, since 2 + 0 + 5 + 52 + 14 + 590 + 2 + 1 = 666.

It is not a de Polignac number, because 205521459021 - 2⁷ = 205521458893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205521459023) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 170415201 + ... + 170416406.

It is an arithmetic number, because the mean of its divisors is an integer number (25107928456).

Almost surely, 2^205521459021 is an apocalyptic number.

It is an amenable number.

205521459021 is a deficient number, since it is larger than the sum of its proper divisors (95773682451).

205521459021 is a wasteful number, since it uses less digits than its factorization.

205521459021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340831680 (or 340831677 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 36.

It can be divided in two parts, 2055 and 21459021, that added together give a triangular number (21461076 = T₆₅₅₁).

The spelling of 205521459021 in words is "two hundred five billion, five hundred twenty-one million, four hundred fifty-nine thousand, twenty-one".