201561251 has 4 divisors (see below), whose sum is σ = 201589872. Its totient is φ = 201532632.

The previous prime is 201561233. The next prime is 201561307. The reversal of 201561251 is 152165102.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 201561251 - 2¹⁸ = 201299107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201560251) 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, 4466 + ... + 20568.

It is an arithmetic number, because the mean of its divisors is an integer number (50397468).

Almost surely, 2^201561251 is an apocalyptic number.

201561251 is a deficient number, since it is larger than the sum of its proper divisors (28621).

201561251 is a wasteful number, since it uses less digits than its factorization.

201561251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28620.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 201561251 is about 14197.2268771053. The cubic root of 201561251 is about 586.3213136501.

The spelling of 201561251 in words is "two hundred one million, five hundred sixty-one thousand, two hundred fifty-one".