50991581 has 2 divisors, whose sum is σ = 50991582. Its totient is φ = 50991580.

The previous prime is 50991557. The next prime is 50991601. The reversal of 50991581 is 18519905.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49632025 + 1359556 = 7045^2 + 1166^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-50991581 is a prime.

It is a super-2 number, since 2×50991581² = 5200282665759122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (50991511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25495790 + 25495791.

It is an arithmetic number, because the mean of its divisors is an integer number (25495791).

Almost surely, 2^50991581 is an apocalyptic number.

It is an amenable number.

50991581 is a deficient number, since it is larger than the sum of its proper divisors (1).

50991581 is an equidigital number, since it uses as much as digits as its factorization.

50991581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16200, while the sum is 38.

The square root of 50991581 is about 7140.8389563132. The cubic root of 50991581 is about 370.8225697447.

The spelling of 50991581 in words is "fifty million, nine hundred ninety-one thousand, five hundred eighty-one".