36991 has 4 divisors (see below), whose sum is σ = 37584. Its totient is φ = 36400.

The previous prime is 36979. The next prime is 36997. The reversal of 36991 is 19963.

36991 = 76² + 77² + ... + 81².

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 36991 - 2⁹ = 36479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (36997) 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, 190 + ... + 331.

It is an arithmetic number, because the mean of its divisors is an integer number (9396).

2³⁶⁹⁹¹ is an apocalyptic number.

36991 is a deficient number, since it is larger than the sum of its proper divisors (593).

36991 is an equidigital number, since it uses as much as digits as its factorization.

36991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592.

The product of its digits is 1458, while the sum is 28.

The square root of 36991 is about 192.3304448079. The cubic root of 36991 is about 33.3195164959.

Subtracting from 36991 its sum of digits (28), we obtain a palindrome (36963).

The spelling of 36991 in words is "thirty-six thousand, nine hundred ninety-one".