205621601 has 6 divisors (see below), whose sum is σ = 210760806. Its totient is φ = 200604800.

The previous prime is 205621583. The next prime is 205621631. The reversal of 205621601 is 106126502.

It can be written as a sum of positive squares in 3 ways, for example, as 12967201 + 192654400 = 3601^2 + 13880^2 .

It is not a de Polignac number, because 205621601 - 2¹⁰ = 205620577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205621631) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 59480 + ... + 62841.

It is an arithmetic number, because the mean of its divisors is an integer number (35126801).

Almost surely, 2^205621601 is an apocalyptic number.

It is an amenable number.

205621601 is a deficient number, since it is larger than the sum of its proper divisors (5139205).

205621601 is an equidigital number, since it uses as much as digits as its factorization.

205621601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122403 (or 122362 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 205621601 is about 14339.5118815112. The cubic root of 205621601 is about 590.2322182703.

The spelling of 205621601 in words is "two hundred five million, six hundred twenty-one thousand, six hundred one".