206121761 has 4 divisors (see below), whose sum is σ = 206219652. Its totient is φ = 206023872.

The previous prime is 206121739. The next prime is 206121767. The reversal of 206121761 is 167121602.

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

It can be written as a sum of positive squares in 2 ways, for example, as 120670225 + 85451536 = 10985^2 + 9244^2 .

It is a cyclic number.

It is not a de Polignac number, because 206121761 - 2¹⁸ = 205859617 is a prime.

It is a super-2 number, since 2×206121761² = 84972360715482242, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 206121761.

It is not an unprimeable number, because it can be changed into a prime (206121767) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45716 + ... + 50021.

It is an arithmetic number, because the mean of its divisors is an integer number (51554913).

Almost surely, 2^206121761 is an apocalyptic number.

It is an amenable number.

206121761 is a deficient number, since it is larger than the sum of its proper divisors (97891).

206121761 is an equidigital number, since it uses as much as digits as its factorization.

206121761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97890.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 206121761 is about 14356.9412132251. The cubic root of 206121761 is about 590.7103968083.

The spelling of 206121761 in words is "two hundred six million, one hundred twenty-one thousand, seven hundred sixty-one".