51661615111 has 4 divisors (see below), whose sum is σ = 51662069712. Its totient is φ = 51661160512.

The previous prime is 51661615099. The next prime is 51661615127. The reversal of 51661615111 is 11151616615.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 11151616615 = 5 ⋅2230323323.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51661615111 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51661615141) 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, 110775 + ... + 339991.

It is an arithmetic number, because the mean of its divisors is an integer number (12915517428).

Almost surely, 2^51661615111 is an apocalyptic number.

51661615111 is a deficient number, since it is larger than the sum of its proper divisors (454601).

51661615111 is a wasteful number, since it uses less digits than its factorization.

51661615111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 454600.

The product of its digits is 5400, while the sum is 34.

The spelling of 51661615111 in words is "fifty-one billion, six hundred sixty-one million, six hundred fifteen thousand, one hundred eleven".