261288641 has 4 divisors (see below), whose sum is σ = 261326784. Its totient is φ = 261250500.

The previous prime is 261288619. The next prime is 261288661. The reversal of 261288641 is 146882162.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-261288641 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261288595 and 261288604.

It is not an unprimeable number, because it can be changed into a prime (261288661) 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, 5645 + ... + 23546.

It is an arithmetic number, because the mean of its divisors is an integer number (65331696).

Almost surely, 2^261288641 is an apocalyptic number.

It is an amenable number.

261288641 is a deficient number, since it is larger than the sum of its proper divisors (38143).

261288641 is an equidigital number, since it uses as much as digits as its factorization.

261288641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38142.

The product of its digits is 36864, while the sum is 38.

The square root of 261288641 is about 16164.4251676328. The cubic root of 261288641 is about 639.3031485862.

The spelling of 261288641 in words is "two hundred sixty-one million, two hundred eighty-eight thousand, six hundred forty-one".