261123657 has 4 divisors (see below), whose sum is σ = 348164880. Its totient is φ = 174082436.

The previous prime is 261123647. The next prime is 261123659. The reversal of 261123657 is 756321162.

261123657 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261123657 - 2¹⁰ = 261122633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261123659) 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, 43520607 + ... + 43520612.

It is an arithmetic number, because the mean of its divisors is an integer number (87041220).

Almost surely, 2^261123657 is an apocalyptic number.

It is an amenable number.

261123657 is a deficient number, since it is larger than the sum of its proper divisors (87041223).

261123657 is an equidigital number, since it uses as much as digits as its factorization.

261123657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87041222.

The product of its digits is 15120, while the sum is 33.

The square root of 261123657 is about 16159.3210562820. The cubic root of 261123657 is about 639.1685630721.

The spelling of 261123657 in words is "two hundred sixty-one million, one hundred twenty-three thousand, six hundred fifty-seven".