35991 has 16 divisors (see below), whose sum is σ = 56320. Its totient is φ = 22680.

The previous prime is 35983. The next prime is 35993. The reversal of 35991 is 19953.

35991 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

35991 is an esthetic number in base 6, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 35991 - 2³ = 35983 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

35991 is an undulating number in base 6.

It is a nialpdrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (35993) 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, 816 + ... + 858.

It is an arithmetic number, because the mean of its divisors is an integer number (3520).

2³⁵⁹⁹¹ is an apocalyptic number.

35991 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

35991 is a deficient number, since it is larger than the sum of its proper divisors (20329).

35991 is a wasteful number, since it uses less digits than its factorization.

35991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83 (or 77 counting only the distinct ones).

The product of its digits is 1215, while the sum is 27.

The square root of 35991 is about 189.7129410451. The cubic root of 35991 is about 33.0165206536.

It can be divided in two parts, 3599 and 1, that added together give a square (3600 = 60²).

The spelling of 35991 in words is "thirty-five thousand, nine hundred ninety-one".