121811 has 4 divisors (see below), whose sum is σ = 124824. Its totient is φ = 118800.

The previous prime is 121789. The next prime is 121843. The reversal of 121811 is 118121.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121711) 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, 1445 + ... + 1526.

It is an arithmetic number, because the mean of its divisors is an integer number (31206).

2¹²¹⁸¹¹ is an apocalyptic number.

121811 is a deficient number, since it is larger than the sum of its proper divisors (3013).

121811 is an equidigital number, since it uses as much as digits as its factorization.

121811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3012.

The product of its digits is 16, while the sum is 14.

The square root of 121811 is about 349.0143263535. The cubic root of 121811 is about 49.5711319615.

Adding to 121811 its reverse (118121), we get a palindrome (239932).

It can be divided in two parts, 1 and 21811, that added together give a palindrome (21812).

The spelling of 121811 in words is "one hundred twenty-one thousand, eight hundred eleven".