1200100021 has 16 divisors (see below), whose sum is σ = 1295769600. Its totient is φ = 1107893808.

The previous prime is 1200100019. The next prime is 1200100043. The reversal of 1200100021 is 1200010021.

It is a cyclic number.

It is not a de Polignac number, because 1200100021 - 2¹ = 1200100019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1200099977 and 1200100013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1200100081) 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 15 ways as a sum of consecutive naturals, for example, 210616 + ... + 216238.

It is an arithmetic number, because the mean of its divisors is an integer number (80985600).

Almost surely, 2^1200100021 is an apocalyptic number.

It is an amenable number.

1200100021 is a deficient number, since it is larger than the sum of its proper divisors (95669579).

1200100021 is a wasteful number, since it uses less digits than its factorization.

1200100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5928.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 1200100021 is about 34642.4598000777. The cubic root of 1200100021 is about 1062.6880928548.

Adding to 1200100021 its reverse (1200010021), we get a palindrome (2400110042).

Subtracting from 1200100021 its reverse (1200010021), we obtain a square (90000 = 300²).

The spelling of 1200100021 in words is "one billion, two hundred million, one hundred thousand, twenty-one".