261500401 has 4 divisors (see below), whose sum is σ = 275263600. Its totient is φ = 247737204.

The previous prime is 261500377. The next prime is 261500429. The reversal of 261500401 is 104005162.

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, and also an emirpimes, since its reverse is a distinct semiprime: 104005162 = 2 ⋅52002581.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261500401 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19), and also a Moran number because the ratio is a prime number: 13763179 = 261500401 / (2 + 6 + 1 + 5 + 0 + 0 + 4 + 0 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261500431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6881571 + ... + 6881608.

It is an arithmetic number, because the mean of its divisors is an integer number (68815900).

Almost surely, 2^261500401 is an apocalyptic number.

It is an amenable number.

261500401 is a deficient number, since it is larger than the sum of its proper divisors (13763199).

261500401 is a wasteful number, since it uses less digits than its factorization.

261500401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13763198.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 261500401 is about 16170.9740275594. The cubic root of 261500401 is about 639.4758085717.

Adding to 261500401 its reverse (104005162), we get a palindrome (365505563).

The spelling of 261500401 in words is "two hundred sixty-one million, five hundred thousand, four hundred one".