121540021 has 4 divisors (see below), whose sum is σ = 128689452. Its totient is φ = 114390592.

The previous prime is 121540007. The next prime is 121540033. The reversal of 121540021 is 120045121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 56415121 + 65124900 = 7511^2 + 8070^2 .

It is a cyclic number.

It is not a de Polignac number, because 121540021 - 2⁷ = 121539893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 121539977 and 121540004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121510021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3574690 + ... + 3574723.

It is an arithmetic number, because the mean of its divisors is an integer number (32172363).

Almost surely, 2^121540021 is an apocalyptic number.

It is an amenable number.

121540021 is a deficient number, since it is larger than the sum of its proper divisors (7149431).

121540021 is an equidigital number, since it uses as much as digits as its factorization.

121540021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7149430.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 121540021 is about 11024.5190824816. The cubic root of 121540021 is about 495.3434626115.

Adding to 121540021 its reverse (120045121), we get a palindrome (241585142).

The spelling of 121540021 in words is "one hundred twenty-one million, five hundred forty thousand, twenty-one".