61509811 has 4 divisors (see below), whose sum is σ = 67101624. Its totient is φ = 55918000.

The previous prime is 61509803. The next prime is 61509817. The reversal of 61509811 is 11890516.

61509811 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 is a cyclic number.

It is not a de Polignac number, because 61509811 - 2³ = 61509803 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61509817) 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, 2795890 + ... + 2795911.

It is an arithmetic number, because the mean of its divisors is an integer number (16775406).

Almost surely, 2^61509811 is an apocalyptic number.

61509811 is a deficient number, since it is larger than the sum of its proper divisors (5591813).

61509811 is a wasteful number, since it uses less digits than its factorization.

61509811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5591812.

The product of its (nonzero) digits is 2160, while the sum is 31.

The square root of 61509811 is about 7842.8190722469. The cubic root of 61509811 is about 394.7433273473.

The spelling of 61509811 in words is "sixty-one million, five hundred nine thousand, eight hundred eleven".