30811 has 4 divisors (see below), whose sum is σ = 33624. Its totient is φ = 28000.

The previous prime is 30809. The next prime is 30817. The reversal of 30811 is 11803.

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 30811 - 2¹ = 30809 is a prime.

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 30791 and 30800.

It is not an unprimeable number, because it can be changed into a prime (30817) 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, 1390 + ... + 1411.

It is an arithmetic number, because the mean of its divisors is an integer number (8406).

2³⁰⁸¹¹ is an apocalyptic number.

30811 is the 79-th centered decagonal number.

30811 is a deficient number, since it is larger than the sum of its proper divisors (2813).

30811 is a wasteful number, since it uses less digits than its factorization.

30811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2812.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 30811 is about 175.5306241087. The cubic root of 30811 is about 31.3498353797.

It can be divided in two parts, 30 and 811, that added together give a square (841 = 29²).

The spelling of 30811 in words is "thirty thousand, eight hundred eleven".