122781 has 4 divisors (see below), whose sum is σ = 163712. Its totient is φ = 81852.

The previous prime is 122777. The next prime is 122789. The reversal of 122781 is 187221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 122781 - 2² = 122777 is a prime.

It is a super-2 number, since 2×122781² = 30150347922, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (122789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20461 + ... + 20466.

It is an arithmetic number, because the mean of its divisors is an integer number (40928).

2¹²²⁷⁸¹ is an apocalyptic number.

It is an amenable number.

122781 is a deficient number, since it is larger than the sum of its proper divisors (40931).

122781 is an equidigital number, since it uses as much as digits as its factorization.

122781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40930.

The product of its digits is 224, while the sum is 21.

The square root of 122781 is about 350.4011986281. The cubic root of 122781 is about 49.7023651184.

Subtracting from 122781 its sum of digits (21), we obtain a triangular number (122760 = T₄₉₅).

It can be divided in two parts, 122 and 781, that added together give a triangular number (903 = T₄₂).

The spelling of 122781 in words is "one hundred twenty-two thousand, seven hundred eighty-one".