261161251 has 16 divisors (see below), whose sum is σ = 308931840. Its totient is φ = 218449440.

The previous prime is 261161239. The next prime is 261161273. The reversal of 261161251 is 152161162.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 261161251 - 2¹¹ = 261159203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261161221) 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 15 ways as a sum of consecutive naturals, for example, 17305 + ... + 28666.

It is an arithmetic number, because the mean of its divisors is an integer number (19308240).

Almost surely, 2^261161251 is an apocalyptic number.

261161251 is a deficient number, since it is larger than the sum of its proper divisors (47770589).

261161251 is a wasteful number, since it uses less digits than its factorization.

261161251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46026.

The product of its digits is 720, while the sum is 25.

The square root of 261161251 is about 16160.4842439823. The cubic root of 261161251 is about 639.1992353217.

The spelling of 261161251 in words is "two hundred sixty-one million, one hundred sixty-one thousand, two hundred fifty-one".