201561555 has 32 divisors (see below), whose sum is σ = 348828480. Its totient is φ = 98795520.

The previous prime is 201561539. The next prime is 201561583. The reversal of 201561555 is 555165102.

It is not a de Polignac number, because 201561555 - 2⁴ = 201561539 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 44851 + ... + 49139.

It is an arithmetic number, because the mean of its divisors is an integer number (10900890).

Almost surely, 2^201561555 is an apocalyptic number.

201561555 is a deficient number, since it is larger than the sum of its proper divisors (147266925).

201561555 is a wasteful number, since it uses less digits than its factorization.

201561555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4551.

The product of its (nonzero) digits is 7500, while the sum is 30.

The square root of 201561555 is about 14197.2375834174. The cubic root of 201561555 is about 586.3216084184.

The spelling of 201561555 in words is "two hundred one million, five hundred sixty-one thousand, five hundred fifty-five".