206510505021 has 32 divisors (see below), whose sum is σ = 307145731200. Its totient is φ = 137132714880.

The previous prime is 206510504989. The next prime is 206510505023. The reversal of 206510505021 is 120505015602.

206510505021 is a `hidden beast` number, since 2 + 0 + 651 + 0 + 5 + 0 + 5 + 0 + 2 + 1 = 666.

206510505021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 206510505021 - 2⁵ = 206510504989 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 (206510505023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8143041 + ... + 8168361.

It is an arithmetic number, because the mean of its divisors is an integer number (9598304100).

Almost surely, 2^206510505021 is an apocalyptic number.

It is an amenable number.

206510505021 is a deficient number, since it is larger than the sum of its proper divisors (100635226179).

206510505021 is a wasteful number, since it uses less digits than its factorization.

206510505021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26506 (or 26500 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The spelling of 206510505021 in words is "two hundred six billion, five hundred ten million, five hundred five thousand, twenty-one".