51061111660491 has 4 divisors (see below), whose sum is σ = 68081482213992. Its totient is φ = 34040741106992.

The previous prime is 51061111660477. The next prime is 51061111660499. The reversal of 51061111660491 is 19406611116015.

It is a happy number.

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 51061111660491 - 2⁵ = 51061111660459 is a prime.

It is a super-2 number, since 2×51061111660491² (a number of 28 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51061111660499) 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, 8510185276746 + ... + 8510185276751.

It is an arithmetic number, because the mean of its divisors is an integer number (17020370553498).

Almost surely, 2^{51061111660491} is an apocalyptic number.

51061111660491 is a deficient number, since it is larger than the sum of its proper divisors (17020370553501).

51061111660491 is a wasteful number, since it uses less digits than its factorization.

51061111660491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17020370553500.

The product of its (nonzero) digits is 38880, while the sum is 42.

The spelling of 51061111660491 in words is "fifty-one trillion, sixty-one billion, one hundred eleven million, six hundred sixty thousand, four hundred ninety-one".