12120021 has 6 divisors (see below), whose sum is σ = 17506710.
Its totient is φ = 8080008.
The previous prime is 12120019. The next prime is 12120047. The reversal of 12120021 is 12002121.
It can be written as a sum of positive squares in only one way, i.e., 8468100 + 3651921 = 2910^2 + 1911^2
It is not a de Polignac number, because 12120021 - 21 = 12120019 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 1346669 = 12120021 / (1 + 2 + 1 + 2 + 0 + 0 + 2 + 1).
It is a Curzon number.
It is a junction number, because it is equal to n+sod(n) for n = 12119985 and 12120012.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (12120001) by changing a digit.
It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 673326 + ... + 673343.
It is an arithmetic number, because the mean of its divisors is an integer number (2917785).
Almost surely, 212120021 is an apocalyptic number.
It is an amenable number.
12120021 is a deficient number, since it is larger than the sum of its proper divisors (5386689).
12120021 is a wasteful number, since it uses less digits than its factorization.
12120021 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1346675 (or 1346672 counting only the distinct ones).
The product of its (nonzero) digits is 8, while the sum is 9.
The square root of 12120021 is about 3481.3820531507.
The cubic root of 12120021 is about 229.7035942353.
Adding to 12120021 its reverse (12002121), we get a palindrome (24122142).
The spelling of 12120021 in words is "twelve million, one hundred twenty thousand, twenty-one".