50009991 has 4 divisors (see below), whose sum is σ = 66679992. Its totient is φ = 33339992.

The previous prime is 50009969. The next prime is 50010001. The reversal of 50009991 is 19990005.

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 50009991 - 2¹⁰ = 50008967 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (50009941) 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, 8334996 + ... + 8335001.

It is an arithmetic number, because the mean of its divisors is an integer number (16669998).

Almost surely, 2^50009991 is an apocalyptic number.

50009991 is a deficient number, since it is larger than the sum of its proper divisors (16670001).

50009991 is a wasteful number, since it uses less digits than its factorization.

50009991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16670000.

The product of its (nonzero) digits is 3645, while the sum is 33.

The square root of 50009991 is about 7071.7742469624. The cubic root of 50009991 is about 368.4276863356.

Adding to 50009991 its reverse (19990005), we get a palindrome (69999996).

The spelling of 50009991 in words is "fifty million, nine thousand, nine hundred ninety-one".