121811823 has 16 divisors (see below), whose sum is σ = 206242560. Its totient is φ = 69606648.

The previous prime is 121811801. The next prime is 121811839. The reversal of 121811823 is 328118121.

It is not a de Polignac number, because 121811823 - 2⁸ = 121811567 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121811843) 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, 322065 + ... + 322442.

It is an arithmetic number, because the mean of its divisors is an integer number (12890160).

Almost surely, 2^121811823 is an apocalyptic number.

121811823 is a deficient number, since it is larger than the sum of its proper divisors (84430737).

121811823 is an equidigital number, since it uses as much as digits as its factorization.

121811823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644523 (or 644517 counting only the distinct ones).

The product of its digits is 768, while the sum is 27.

The square root of 121811823 is about 11036.8393573523. The cubic root of 121811823 is about 495.7124360157.

Adding to 121811823 its reverse (328118121), we get a palindrome (449929944).

It can be divided in two parts, 1218 and 11823, that added together give a triangular number (13041 = T₁₆₁).

The spelling of 121811823 in words is "one hundred twenty-one million, eight hundred eleven thousand, eight hundred twenty-three".