121857 has 8 divisors (see below), whose sum is σ = 164160. Its totient is φ = 80400.

The previous prime is 121853. The next prime is 121867. The reversal of 121857 is 758121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 121857 - 2² = 121853 is a prime.

121857 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 319 + ... + 587.

It is an arithmetic number, because the mean of its divisors is an integer number (20520).

It is a Proth number, since it is equal to 119 ⋅ 2¹⁰ + 1 and 119 < 2¹⁰.

2¹²¹⁸⁵⁷ is an apocalyptic number.

It is an amenable number.

121857 is a deficient number, since it is larger than the sum of its proper divisors (42303).

121857 is a wasteful number, since it uses less digits than its factorization.

121857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 423.

The product of its digits is 560, while the sum is 24.

The square root of 121857 is about 349.0802200068. The cubic root of 121857 is about 49.5773710946.

Adding to 121857 its reverse (758121), we get a palindrome (879978).

It can be divided in two parts, 1218 and 57, that added together give a triangular number (1275 = T₅₀).

The spelling of 121857 in words is "one hundred twenty-one thousand, eight hundred fifty-seven".