65561409 has 9 divisors (see below), whose sum is σ = 94734913. Its totient is φ = 43691412.

The previous prime is 65561407. The next prime is 65561413. The reversal of 65561409 is 90416556.

The square root of 65561409 is 8097.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 65561409 - 2¹ = 65561407 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65561407) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 22942 + ... + 25640.

Almost surely, 2^65561409 is an apocalyptic number.

65561409 is the 8097-th square number.

65561409 is the 4049-th centered octagonal number.

It is an amenable number.

65561409 is a deficient number, since it is larger than the sum of its proper divisors (29173504).

65561409 is an frugal number, since it uses more digits than its factorization.

65561409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5404 (or 2702 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The cubic root of 65561409 is about 403.2268342697.

Multiplying 65561409 by its sum of digits (36), we get a square (2360210724 = 48582²).

Multiplying 65561409 by its product of nonzero digits (32400), we get a square (2124189651600 = 1457460²).

The spelling of 65561409 in words is "sixty-five million, five hundred sixty-one thousand, four hundred nine".