51091504661 has 4 divisors (see below), whose sum is σ = 52279679232. Its totient is φ = 49903330092.

The previous prime is 51091504637. The next prime is 51091504753. The reversal of 51091504661 is 16640519015.

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 51091504661 - 2¹⁰ = 51091503637 is a prime.

It is a super-2 number, since 2×51091504661² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51091504601) 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, 594087221 + ... + 594087306.

It is an arithmetic number, because the mean of its divisors is an integer number (13069919808).

Almost surely, 2^51091504661 is an apocalyptic number.

It is an amenable number.

51091504661 is a deficient number, since it is larger than the sum of its proper divisors (1188174571).

51091504661 is a wasteful number, since it uses less digits than its factorization.

51091504661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1188174570.

The product of its (nonzero) digits is 32400, while the sum is 38.

The spelling of 51091504661 in words is "fifty-one billion, ninety-one million, five hundred four thousand, six hundred sixty-one".