261131566 has 8 divisors (see below), whose sum is σ = 395735760. Its totient is φ = 129219648.

The previous prime is 261131557. The next prime is 261131567. The reversal of 261131566 is 665131162.

261131566 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×261131566² = 136379389523224712, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261131567) 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, 672826 + ... + 673213.

It is an arithmetic number, because the mean of its divisors is an integer number (49466970).

Almost surely, 2^261131566 is an apocalyptic number.

261131566 is a deficient number, since it is larger than the sum of its proper divisors (134604194).

261131566 is a wasteful number, since it uses less digits than its factorization.

261131566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1346138.

The product of its digits is 6480, while the sum is 31.

The square root of 261131566 is about 16159.5657738690. The cubic root of 261131566 is about 639.1750161235.

The spelling of 261131566 in words is "two hundred sixty-one million, one hundred thirty-one thousand, five hundred sixty-six".