121581 has 20 divisors (see below), whose sum is σ = 193600. Its totient is φ = 75816.

The previous prime is 121579. The next prime is 121591. The reversal of 121581 is 185121.

It is not a de Polignac number, because 121581 - 2¹ = 121579 is a prime.

It is a super-2 number, since 2×121581² = 29563879122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

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

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1500 + ... + 1578.

It is an arithmetic number, because the mean of its divisors is an integer number (9680).

2¹²¹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

121581 is a deficient number, since it is larger than the sum of its proper divisors (72019).

121581 is an equidigital number, since it uses as much as digits as its factorization.

121581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110 (or 101 counting only the distinct ones).

The product of its digits is 80, while the sum is 18.

The square root of 121581 is about 348.6846713006. The cubic root of 121581 is about 49.5399127126.

It can be divided in two parts, 1215 and 81, that added together give a 4-th power (1296 = 6⁴).

The spelling of 121581 in words is "one hundred twenty-one thousand, five hundred eighty-one".