61565909 has 4 divisors (see below), whose sum is σ = 64806240. Its totient is φ = 58325580.

The previous prime is 61565899. The next prime is 61565921. The reversal of 61565909 is 90956516.

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 61565909 - 2²⁰ = 60517333 is a prime.

It is a super-2 number, since 2×61565909² = 7580722301992562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61565929) 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, 1620137 + ... + 1620174.

It is an arithmetic number, because the mean of its divisors is an integer number (16201560).

Almost surely, 2^61565909 is an apocalyptic number.

It is an amenable number.

61565909 is a deficient number, since it is larger than the sum of its proper divisors (3240331).

61565909 is a wasteful number, since it uses less digits than its factorization.

61565909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3240330.

The product of its (nonzero) digits is 72900, while the sum is 41.

The square root of 61565909 is about 7846.3946497739. The cubic root of 61565909 is about 394.8632951066.

The spelling of 61565909 in words is "sixty-one million, five hundred sixty-five thousand, nine hundred nine".