61181890561 has 4 divisors (see below), whose sum is σ = 66743880624. Its totient is φ = 55619900500.

The previous prime is 61181890559. The next prime is 61181890571. The reversal of 61181890561 is 16509818116.

It is a happy number.

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 61181890561 - 2¹ = 61181890559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61181890571) 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, 2780995015 + ... + 2780995036.

It is an arithmetic number, because the mean of its divisors is an integer number (16685970156).

Almost surely, 2^61181890561 is an apocalyptic number.

It is an amenable number.

61181890561 is a deficient number, since it is larger than the sum of its proper divisors (5561990063).

61181890561 is a wasteful number, since it uses less digits than its factorization.

61181890561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5561990062.

The product of its (nonzero) digits is 103680, while the sum is 46.

The spelling of 61181890561 in words is "sixty-one billion, one hundred eighty-one million, eight hundred ninety thousand, five hundred sixty-one".