261561693 has 4 divisors (see below), whose sum is σ = 348748928. Its totient is φ = 174374460.

The previous prime is 261561679. The next prime is 261561697. The reversal of 261561693 is 396165162.

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 not a de Polignac number, because 261561693 - 2⁵ = 261561661 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 (261561697) 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, 43593613 + ... + 43593618.

It is an arithmetic number, because the mean of its divisors is an integer number (87187232).

Almost surely, 2^261561693 is an apocalyptic number.

It is an amenable number.

261561693 is a deficient number, since it is larger than the sum of its proper divisors (87187235).

261561693 is an equidigital number, since it uses as much as digits as its factorization.

261561693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87187234.

The product of its digits is 58320, while the sum is 39.

The square root of 261561693 is about 16172.8690404640. The cubic root of 261561693 is about 639.5257660342.

The spelling of 261561693 in words is "two hundred sixty-one million, five hundred sixty-one thousand, six hundred ninety-three".