121681 has 4 divisors (see below), whose sum is σ = 139072. Its totient is φ = 104292.

The previous prime is 121661. The next prime is 121687. The reversal of 121681 is 186121.

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 a cyclic number.

It is not a de Polignac number, because 121681 - 2⁷ = 121553 is a prime.

It is a super-2 number, since 2×121681² = 29612531522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121687) 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, 8685 + ... + 8698.

It is an arithmetic number, because the mean of its divisors is an integer number (34768).

2¹²¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

121681 is a deficient number, since it is larger than the sum of its proper divisors (17391).

121681 is an equidigital number, since it uses as much as digits as its factorization.

121681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17390.

The product of its digits is 96, while the sum is 19.

The square root of 121681 is about 348.8280378639. The cubic root of 121681 is about 49.5534911327.

The spelling of 121681 in words is "one hundred twenty-one thousand, six hundred eighty-one".