261501761 has 4 divisors (see below), whose sum is σ = 261660672. Its totient is φ = 261342852.

The previous prime is 261501727. The next prime is 261501767. The reversal of 261501761 is 167105162.

261501761 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 261501761 - 2¹⁸ = 261239617 is a prime.

It is a super-2 number, since 2×261501761² = 136766342012202242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261501767) 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, 76961 + ... + 80286.

It is an arithmetic number, because the mean of its divisors is an integer number (65415168).

Almost surely, 2^261501761 is an apocalyptic number.

It is an amenable number.

261501761 is a deficient number, since it is larger than the sum of its proper divisors (158911).

261501761 is a wasteful number, since it uses less digits than its factorization.

261501761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158910.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 261501761 is about 16171.0160781566. The cubic root of 261501761 is about 639.4769171558.

It can be divided in two parts, 261501 and 761, that added together give a palindrome (262262).

The spelling of 261501761 in words is "two hundred sixty-one million, five hundred one thousand, seven hundred sixty-one".