121561 has 8 divisors (see below), whose sum is σ = 136224. Its totient is φ = 107520.

The previous prime is 121559. The next prime is 121571. The reversal of 121561 is 165121.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 121561 - 2¹ = 121559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 345 + ... + 601.

It is an arithmetic number, because the mean of its divisors is an integer number (17028).

2¹²¹⁵⁶¹ is an apocalyptic number.

121561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

121561 is a deficient number, since it is larger than the sum of its proper divisors (14663).

121561 is a wasteful number, since it uses less digits than its factorization.

121561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311.

The product of its digits is 60, while the sum is 16.

The square root of 121561 is about 348.6559909137. The cubic root of 121561 is about 49.5371961352.

Adding to 121561 its reverse (165121), we get a palindrome (286682).

The spelling of 121561 in words is "one hundred twenty-one thousand, five hundred sixty-one".