1200120021 has 12 divisors (see below), whose sum is σ = 1793283180. Its totient is φ = 772490880.

The previous prime is 1200120017. The next prime is 1200120037. The reversal of 1200120021 is 1200210021.

It can be written as a sum of positive squares in 2 ways, for example, as 563112900 + 637007121 = 23730^2 + 25239^2 .

It is not a de Polignac number, because 1200120021 - 2² = 1200120017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 1200119985 and 1200120012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1200120011) 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 11 ways as a sum of consecutive naturals, for example, 2298820 + ... + 2299341.

It is an arithmetic number, because the mean of its divisors is an integer number (149440265).

Almost surely, 2^1200120021 is an apocalyptic number.

It is an amenable number.

1200120021 is a deficient number, since it is larger than the sum of its proper divisors (593163159).

1200120021 is a wasteful number, since it uses less digits than its factorization.

1200120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4598196 (or 4598193 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 1200120021 is about 34642.7484619797. The cubic root of 1200120021 is about 1062.6939961527.

Adding to 1200120021 its reverse (1200210021), we get a palindrome (2400330042).

Subtracting 1200120021 from its reverse (1200210021), we obtain a square (90000 = 300²).

The spelling of 1200120021 in words is "one billion, two hundred million, one hundred twenty thousand, twenty-one".