1200021001 has 4 divisors (see below), whose sum is σ = 1220360400. Its totient is φ = 1179681604.

The previous prime is 1200020999. The next prime is 1200021013. The reversal of 1200021001 is 1001200021.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1001200021 = 2437 ⋅410833.

It is a cyclic number.

It is not a de Polignac number, because 1200021001 - 2¹ = 1200020999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1200021101) 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, 10169611 + ... + 10169728.

It is an arithmetic number, because the mean of its divisors is an integer number (305090100).

Almost surely, 2^1200021001 is an apocalyptic number.

It is an amenable number.

1200021001 is a deficient number, since it is larger than the sum of its proper divisors (20339399).

1200021001 is an equidigital number, since it uses as much as digits as its factorization.

1200021001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20339398.

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

The square root of 1200021001 is about 34641.3192733764. The cubic root of 1200021001 is about 1062.6647682833.

Adding to 1200021001 its reverse (1001200021), we get a palindrome (2201221022).

The spelling of 1200021001 in words is "one billion, two hundred million, twenty-one thousand, one".