51209540091 has 32 divisors (see below), whose sum is σ = 78430795520. Its totient is φ = 33001903872.

The previous prime is 51209540059. The next prime is 51209540111. The reversal of 51209540091 is 19004590215.

51209540091 is a `hidden beast` number, since 5 + 1 + 20 + 9 + 540 + 0 + 91 = 666.

It is not a de Polignac number, because 51209540091 - 2⁵ = 51209540059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51209540891) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 114745 + ... + 339978.

It is an arithmetic number, because the mean of its divisors is an integer number (2450962360).

Almost surely, 2^51209540091 is an apocalyptic number.

51209540091 is a deficient number, since it is larger than the sum of its proper divisors (27221255429).

51209540091 is a wasteful number, since it uses less digits than its factorization.

51209540091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 454872 (or 454866 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 36.

The spelling of 51209540091 in words is "fifty-one billion, two hundred nine million, five hundred forty thousand, ninety-one".