205621557 has 12 divisors (see below), whose sum is σ = 276944640. Its totient is φ = 135703600.

The previous prime is 205621531. The next prime is 205621567. The reversal of 205621557 is 755126502.

It is not a de Polignac number, because 205621557 - 2²² = 201427253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205621567) 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 11 ways as a sum of consecutive naturals, for example, 27244 + ... + 33962.

It is an arithmetic number, because the mean of its divisors is an integer number (23078720).

Almost surely, 2^205621557 is an apocalyptic number.

It is an amenable number.

205621557 is a deficient number, since it is larger than the sum of its proper divisors (71323083).

205621557 is an equidigital number, since it uses as much as digits as its factorization.

205621557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6924 (or 6823 counting only the distinct ones).

The product of its (nonzero) digits is 21000, while the sum is 33.

The square root of 205621557 is about 14339.5103472887. The cubic root of 205621557 is about 590.2321761699.

The spelling of 205621557 in words is "two hundred five million, six hundred twenty-one thousand, five hundred fifty-seven".