121819561 has 4 divisors (see below), whose sum is σ = 121870224. Its totient is φ = 121768900.

The previous prime is 121819549. The next prime is 121819571. The reversal of 121819561 is 165918121.

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, and also an emirpimes, since its reverse is a distinct semiprime: 165918121 = 727 ⋅228223.

It is a cyclic number.

It is not a de Polignac number, because 121819561 - 2¹¹ = 121817513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121819531) 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, 21535 + ... + 26596.

It is an arithmetic number, because the mean of its divisors is an integer number (30467556).

Almost surely, 2^121819561 is an apocalyptic number.

It is an amenable number.

121819561 is a deficient number, since it is larger than the sum of its proper divisors (50663).

121819561 is an equidigital number, since it uses as much as digits as its factorization.

121819561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50662.

The product of its digits is 4320, while the sum is 34.

The square root of 121819561 is about 11037.1899050438. The cubic root of 121819561 is about 495.7229323740.

The spelling of 121819561 in words is "one hundred twenty-one million, eight hundred nineteen thousand, five hundred sixty-one".