121335721 has 4 divisors (see below), whose sum is σ = 130669252. Its totient is φ = 112002192.

The previous prime is 121335719. The next prime is 121335743. The reversal of 121335721 is 127533121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127533121 = 379 ⋅336499.

It can be written as a sum of positive squares in 2 ways, for example, as 12425625 + 108910096 = 3525^2 + 10436^2 .

It is a cyclic number.

It is not a de Polignac number, because 121335721 - 2¹ = 121335719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121335701) 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, 4666746 + ... + 4666771.

It is an arithmetic number, because the mean of its divisors is an integer number (32667313).

Almost surely, 2^121335721 is an apocalyptic number.

It is an amenable number.

121335721 is a deficient number, since it is larger than the sum of its proper divisors (9333531).

121335721 is an equidigital number, since it uses as much as digits as its factorization.

121335721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9333530.

The product of its digits is 1260, while the sum is 25.

The square root of 121335721 is about 11015.2494751594. The cubic root of 121335721 is about 495.0657614226.

Adding to 121335721 its reverse (127533121), we get a palindrome (248868842).

The spelling of 121335721 in words is "one hundred twenty-one million, three hundred thirty-five thousand, seven hundred twenty-one".