205421761 has 8 divisors (see below), whose sum is σ = 225006120. Its totient is φ = 186670848.

The previous prime is 205421747. The next prime is 205421771. The reversal of 205421761 is 167124502.

It can be written as a sum of positive squares in 4 ways, for example, as 66912400 + 138509361 = 8180^2 + 11769^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 205421761 - 2⁷ = 205421633 is a prime.

It is a super-2 number, since 2×205421761² = 84396199784682242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205421731) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207846 + ... + 208831.

It is an arithmetic number, because the mean of its divisors is an integer number (28125765).

Almost surely, 2^205421761 is an apocalyptic number.

It is an amenable number.

205421761 is a deficient number, since it is larger than the sum of its proper divisors (19584359).

205421761 is a wasteful number, since it uses less digits than its factorization.

205421761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416723.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 205421761 is about 14332.5420285447. The cubic root of 205421761 is about 590.0409442044.

The spelling of 205421761 in words is "two hundred five million, four hundred twenty-one thousand, seven hundred sixty-one".