61155561 has 8 divisors (see below), whose sum is σ = 83744704. Its totient is φ = 39668400.

The previous prime is 61155553. The next prime is 61155571. The reversal of 61155561 is 16555116.

61155561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 61155561 - 2³ = 61155553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61155541) 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 7 ways as a sum of consecutive naturals, for example, 275365 + ... + 275586.

It is an arithmetic number, because the mean of its divisors is an integer number (10468088).

Almost surely, 2^61155561 is an apocalyptic number.

It is an amenable number.

61155561 is a deficient number, since it is larger than the sum of its proper divisors (22589143).

61155561 is a wasteful number, since it uses less digits than its factorization.

61155561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 550991.

The product of its digits is 4500, while the sum is 30.

The square root of 61155561 is about 7820.2021073627. The cubic root of 61155561 is about 393.9840601830.

It can be divided in two parts, 61155 and 561, that added together give a palindrome (61716).

The spelling of 61155561 in words is "sixty-one million, one hundred fifty-five thousand, five hundred sixty-one".