51206506621 has 4 divisors (see below), whose sum is σ = 51207769312. Its totient is φ = 51205243932.

The previous prime is 51206506609. The next prime is 51206506649. The reversal of 51206506621 is 12660560215.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12660560215 = 5 ⋅2532112043.

It is a cyclic number.

It is not a de Polignac number, because 51206506621 - 2⁷ = 51206506493 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 (51206506921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 568425 + ... + 652318.

It is an arithmetic number, because the mean of its divisors is an integer number (12801942328).

Almost surely, 2^51206506621 is an apocalyptic number.

It is an amenable number.

51206506621 is a deficient number, since it is larger than the sum of its proper divisors (1262691).

51206506621 is a wasteful number, since it uses less digits than its factorization.

51206506621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1262690.

The product of its (nonzero) digits is 21600, while the sum is 34.

The spelling of 51206506621 in words is "fifty-one billion, two hundred six million, five hundred six thousand, six hundred twenty-one".