61309561 has 8 divisors (see below), whose sum is σ = 65421920. Its totient is φ = 57285792.

The previous prime is 61309553. The next prime is 61309571. The reversal of 61309561 is 16590316.

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

It is a cyclic number.

It is not a de Polignac number, because 61309561 - 2³ = 61309553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61309571) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20715 + ... + 23488.

It is an arithmetic number, because the mean of its divisors is an integer number (8177740).

Almost surely, 2^61309561 is an apocalyptic number.

It is an amenable number.

61309561 is a deficient number, since it is larger than the sum of its proper divisors (4112359).

61309561 is a wasteful number, since it uses less digits than its factorization.

61309561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44295.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 61309561 is about 7830.0422093371. The cubic root of 61309561 is about 394.3144890471.

Adding to 61309561 its reverse (16590316), we get a palindrome (77899877).

The spelling of 61309561 in words is "sixty-one million, three hundred nine thousand, five hundred sixty-one".