261391623 has 8 divisors (see below), whose sum is σ = 352115568. Its totient is φ = 172464384.

The previous prime is 261391591. The next prime is 261391633. The reversal of 261391623 is 326193162.

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

It is not a de Polignac number, because 261391623 - 2⁵ = 261391591 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261391633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 448836 + ... + 449417.

It is an arithmetic number, because the mean of its divisors is an integer number (44014446).

Almost surely, 2^261391623 is an apocalyptic number.

261391623 is a deficient number, since it is larger than the sum of its proper divisors (90723945).

261391623 is an equidigital number, since it uses as much as digits as its factorization.

261391623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 898353.

The product of its digits is 11664, while the sum is 33.

The square root of 261391623 is about 16167.6103057935. The cubic root of 261391623 is about 639.3871273221.

The spelling of 261391623 in words is "two hundred sixty-one million, three hundred ninety-one thousand, six hundred twenty-three".