215266261 has 12 divisors (see below), whose sum is σ = 251464620. Its totient is φ = 183738240.

The previous prime is 215266241. The next prime is 215266267. The reversal of 215266261 is 162662512.

It can be written as a sum of positive squares in 2 ways, for example, as 199346161 + 15920100 = 14119^2 + 3990^2 .

It is not a de Polignac number, because 215266261 - 2⁵ = 215266229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215266267) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2695 + ... + 20923.

It is an arithmetic number, because the mean of its divisors is an integer number (20955385).

Almost surely, 2^215266261 is an apocalyptic number.

It is an amenable number.

215266261 is a deficient number, since it is larger than the sum of its proper divisors (36198359).

215266261 is a wasteful number, since it uses less digits than its factorization.

215266261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18484 (or 18477 counting only the distinct ones).

The product of its digits is 8640, while the sum is 31.

The square root of 215266261 is about 14671.9549140529. The cubic root of 215266261 is about 599.3198413020.

The spelling of 215266261 in words is "two hundred fifteen million, two hundred sixty-six thousand, two hundred sixty-one".