61891543993 has 4 divisors (see below), whose sum is σ = 63059309028. Its totient is φ = 60723778960.

The previous prime is 61891543991. The next prime is 61891543997. The reversal of 61891543993 is 39934519816.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 22888058944 + 39003485049 = 151288^2 + 197493^2 .

It is a cyclic number.

It is not a de Polignac number, because 61891543993 - 2¹ = 61891543991 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61891543991) 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, 583882438 + ... + 583882543.

It is an arithmetic number, because the mean of its divisors is an integer number (15764827257).

Almost surely, 2^61891543993 is an apocalyptic number.

It is an amenable number.

61891543993 is a deficient number, since it is larger than the sum of its proper divisors (1167765035).

61891543993 is a wasteful number, since it uses less digits than its factorization.

61891543993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1167765034.

The product of its digits is 6298560, while the sum is 58.

The spelling of 61891543993 in words is "sixty-one billion, eight hundred ninety-one million, five hundred forty-three thousand, nine hundred ninety-three".