1211020001001 has 12 divisors (see below), whose sum is σ = 1749268222260. Its totient is φ = 807338770560.

The previous prime is 1211020000969. The next prime is 1211020001017. The reversal of 1211020001001 is 1001000201121.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 496318841001 + 714701160000 = 704499^2 + 845400^2 .

It is not a de Polignac number, because 1211020001001 - 2⁵ = 1211020000969 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (1211020001041) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 403285 + ... + 1607693.

It is an arithmetic number, because the mean of its divisors is an integer number (145772351855).

Almost surely, 2^{1211020001001} is an apocalyptic number.

It is an amenable number.

1211020001001 is a deficient number, since it is larger than the sum of its proper divisors (538248221259).

1211020001001 is a wasteful number, since it uses less digits than its factorization.

1211020001001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1316136 (or 1316133 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 1211020001001 its reverse (1001000201121), we get a palindrome (2212020202122).

The spelling of 1211020001001 in words is "one trillion, two hundred eleven billion, twenty million, one thousand, one".