261510247 has 4 divisors (see below), whose sum is σ = 263954376. Its totient is φ = 259066120.

The previous prime is 261510241. The next prime is 261510289. The reversal of 261510247 is 742015162.

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 261510247 - 2²³ = 253121639 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 (261510241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1221904 + ... + 1222117.

It is an arithmetic number, because the mean of its divisors is an integer number (65988594).

Almost surely, 2^261510247 is an apocalyptic number.

261510247 is a deficient number, since it is larger than the sum of its proper divisors (2444129).

261510247 is a wasteful number, since it uses less digits than its factorization.

261510247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2444128.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 261510247 is about 16171.2784590458. The cubic root of 261510247 is about 639.4838343080.

The spelling of 261510247 in words is "two hundred sixty-one million, five hundred ten thousand, two hundred forty-seven".