261488639 has 4 divisors (see below), whose sum is σ = 265775400. Its totient is φ = 257201880.

The previous prime is 261488609. The next prime is 261488641. The reversal of 261488639 is 936884162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261488639 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261488593 and 261488602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261488609) 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, 2143289 + ... + 2143410.

It is an arithmetic number, because the mean of its divisors is an integer number (66443850).

Almost surely, 2^261488639 is an apocalyptic number.

261488639 is a deficient number, since it is larger than the sum of its proper divisors (4286761).

261488639 is an equidigital number, since it uses as much as digits as its factorization.

261488639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4286760.

The product of its digits is 497664, while the sum is 47.

The square root of 261488639 is about 16170.6103471700. The cubic root of 261488639 is about 639.4662207887.

The spelling of 261488639 in words is "two hundred sixty-one million, four hundred eighty-eight thousand, six hundred thirty-nine".