261216051 has 4 divisors (see below), whose sum is σ = 348288072. Its totient is φ = 174144032.

The previous prime is 261216031. The next prime is 261216073. The reversal of 261216051 is 150612162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261216051 - 2⁵ = 261216019 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261216001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43536006 + ... + 43536011.

It is an arithmetic number, because the mean of its divisors is an integer number (87072018).

Almost surely, 2^261216051 is an apocalyptic number.

261216051 is a deficient number, since it is larger than the sum of its proper divisors (87072021).

261216051 is an equidigital number, since it uses as much as digits as its factorization.

261216051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87072020.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 261216051 is about 16162.1796487974. The cubic root of 261216051 is about 639.2439403564.

The spelling of 261216051 in words is "two hundred sixty-one million, two hundred sixteen thousand, fifty-one".