61205509 has 4 divisors (see below), whose sum is σ = 62208940. Its totient is φ = 60202080.

The previous prime is 61205483. The next prime is 61205519. The reversal of 61205509 is 90550216.

61205509 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.

It can be written as a sum of positive squares in 2 ways, for example, as 26040609 + 35164900 = 5103^2 + 5930^2 .

It is a cyclic number.

It is not a de Polignac number, because 61205509 - 2⁵ = 61205477 is a prime.

It is a super-2 number, since 2×61205509² = 7492228663898162, 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 (61205519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 501624 + ... + 501745.

It is an arithmetic number, because the mean of its divisors is an integer number (15552235).

Almost surely, 2^61205509 is an apocalyptic number.

It is an amenable number.

61205509 is a deficient number, since it is larger than the sum of its proper divisors (1003431).

61205509 is a wasteful number, since it uses less digits than its factorization.

61205509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1003430.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 61205509 is about 7823.3949791635. The cubic root of 61205509 is about 394.0912914279.

The spelling of 61205509 in words is "sixty-one million, two hundred five thousand, five hundred nine".