65561261 has 4 divisors (see below), whose sum is σ = 65577792. Its totient is φ = 65544732.

The previous prime is 65561239. The next prime is 65561269. The reversal of 65561261 is 16216556.

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-65561261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65561269) 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, 1646 + ... + 11568.

It is an arithmetic number, because the mean of its divisors is an integer number (16394448).

Almost surely, 2^65561261 is an apocalyptic number.

It is an amenable number.

65561261 is a deficient number, since it is larger than the sum of its proper divisors (16531).

65561261 is an equidigital number, since it uses as much as digits as its factorization.

65561261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16530.

The product of its digits is 10800, while the sum is 32.

The square root of 65561261 is about 8096.9908608075. The cubic root of 65561261 is about 403.2265308512.

It can be divided in two parts, 655 and 61261, that added together give a palindrome (61916).

The spelling of 65561261 in words is "sixty-five million, five hundred sixty-one thousand, two hundred sixty-one".