61513121791 has 4 divisors (see below), whose sum is σ = 67105223784. Its totient is φ = 55921019800.

The previous prime is 61513121779. The next prime is 61513121797. The reversal of 61513121791 is 19712131516.

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 61513121791 - 2⁹ = 61513121279 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 61513121791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61513121797) 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, 2796050980 + ... + 2796051001.

It is an arithmetic number, because the mean of its divisors is an integer number (16776305946).

Almost surely, 2^61513121791 is an apocalyptic number.

61513121791 is a deficient number, since it is larger than the sum of its proper divisors (5592101993).

61513121791 is a wasteful number, since it uses less digits than its factorization.

61513121791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5592101992.

The product of its digits is 11340, while the sum is 37.

The spelling of 61513121791 in words is "sixty-one billion, five hundred thirteen million, one hundred twenty-one thousand, seven hundred ninety-one".