12121357 has 4 divisors (see below), whose sum is σ = 12834396. Its totient is φ = 11408320.

The previous prime is 12121337. The next prime is 12121367. The reversal of 12121357 is 75312121.

It is a happy number.

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 4247721 + 7873636 = 2061^2 + 2806^2 .

It is a cyclic number.

It is not a de Polignac number, because 12121357 - 2¹¹ = 12119309 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12121327) 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, 356494 + ... + 356527.

It is an arithmetic number, because the mean of its divisors is an integer number (3208599).

Almost surely, 2^12121357 is an apocalyptic number.

12121357 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

12121357 is a deficient number, since it is larger than the sum of its proper divisors (713039).

12121357 is an equidigital number, since it uses as much as digits as its factorization.

12121357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 713038.

The product of its digits is 420, while the sum is 22.

The square root of 12121357 is about 3481.5739256836. The cubic root of 12121357 is about 229.7120340646.

Adding to 12121357 its reverse (75312121), we get a palindrome (87433478).

The spelling of 12121357 in words is "twelve million, one hundred twenty-one thousand, three hundred fifty-seven".