347991 has 16 divisors (see below), whose sum is σ = 539904. Its totient is φ = 195264.

The previous prime is 347989. The next prime is 347993. The reversal of 347991 is 199743.

It is an interprime number because it is at equal distance from previous prime (347989) and next prime (347993).

It is not a de Polignac number, because 347991 - 2¹ = 347989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (347993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1420 + ... + 1646.

It is an arithmetic number, because the mean of its divisors is an integer number (33744).

2³⁴⁷⁹⁹¹ is an apocalyptic number.

347991 is a deficient number, since it is larger than the sum of its proper divisors (191913).

347991 is a wasteful number, since it uses less digits than its factorization.

347991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310.

The product of its digits is 6804, while the sum is 33.

The square root of 347991 is about 589.9076198864. The cubic root of 347991 is about 70.3378901884.

It can be divided in two parts, 3479 and 91, that added together give a triangular number (3570 = T₈₄).

The spelling of 347991 in words is "three hundred forty-seven thousand, nine hundred ninety-one".