351991 has 2 divisors, whose sum is σ = 351992. Its totient is φ = 351990.

The previous prime is 351971. The next prime is 352007. The reversal of 351991 is 199153.

It is a strong prime.

It is an emirp because it is prime and its reverse (199153) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 351991 - 2⁵ = 351959 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (351931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 175995 + 175996.

It is an arithmetic number, because the mean of its divisors is an integer number (175996).

2³⁵¹⁹⁹¹ is an apocalyptic number.

351991 is a deficient number, since it is larger than the sum of its proper divisors (1).

351991 is an equidigital number, since it uses as much as digits as its factorization.

351991 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 351991 is about 593.2882941707. The cubic root of 351991 is about 70.6063649375.

The spelling of 351991 in words is "three hundred fifty-one thousand, nine hundred ninety-one".