513991 has 2 divisors, whose sum is σ = 513992. Its totient is φ = 513990.

The previous prime is 513977. The next prime is 514001. The reversal of 513991 is 199315.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 513991 - 2⁹ = 513479 is a prime.

513991 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (513691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 256995 + 256996.

It is an arithmetic number, because the mean of its divisors is an integer number (256996).

2⁵¹³⁹⁹¹ is an apocalyptic number.

513991 is a deficient number, since it is larger than the sum of its proper divisors (1).

513991 is an equidigital number, since it uses as much as digits as its factorization.

513991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1215, while the sum is 28.

The square root of 513991 is about 716.9316564360. The cubic root of 513991 is about 80.1035637906.

The spelling of 513991 in words is "five hundred thirteen thousand, nine hundred ninety-one".