361991 has 4 divisors (see below), whose sum is σ = 413712. Its totient is φ = 310272.

The previous prime is 361979. The next prime is 361993. The reversal of 361991 is 199163.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199163 = 277 ⋅719.

It is a cyclic number.

It is not a de Polignac number, because 361991 - 2⁶ = 361927 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (361993) 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, 25850 + ... + 25863.

It is an arithmetic number, because the mean of its divisors is an integer number (103428).

2³⁶¹⁹⁹¹ is an apocalyptic number.

361991 is a deficient number, since it is larger than the sum of its proper divisors (51721).

361991 is an equidigital number, since it uses as much as digits as its factorization.

361991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51720.

The product of its digits is 1458, while the sum is 29.

The square root of 361991 is about 601.6568789601. The cubic root of 361991 is about 71.2687690371.

The spelling of 361991 in words is "three hundred sixty-one thousand, nine hundred ninety-one".