61506055561 has 4 divisors (see below), whose sum is σ = 64743216400. Its totient is φ = 58268894724.

The previous prime is 61506055549. The next prime is 61506055627. The reversal of 61506055561 is 16555060516.

61506055561 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, 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 61506055561 - 2⁹ = 61506055049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61506052561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1618580391 + ... + 1618580428.

It is an arithmetic number, because the mean of its divisors is an integer number (16185804100).

Almost surely, 2^61506055561 is an apocalyptic number.

It is an amenable number.

61506055561 is a deficient number, since it is larger than the sum of its proper divisors (3237160839).

61506055561 is a wasteful number, since it uses less digits than its factorization.

61506055561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3237160838.

The product of its (nonzero) digits is 135000, while the sum is 40.

The spelling of 61506055561 in words is "sixty-one billion, five hundred six million, fifty-five thousand, five hundred sixty-one".