1211983011801 has 9 divisors (see below), whose sum is σ = 1750646898741. Its totient is φ = 807986472732.

The previous prime is 1211983011793. The next prime is 1211983011823. The reversal of 1211983011801 is 1081103891121.

The square root of 1211983011801 is 1100901.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1211983011801 - 2³ = 1211983011793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1211983011881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3119220 + ... + 3486186.

Almost surely, 2^{1211983011801} is an apocalyptic number.

1211983011801 is the 1100901-st square number.

1211983011801 is the 550451-st centered octagonal number.

It is an amenable number.

1211983011801 is a deficient number, since it is larger than the sum of its proper divisors (538663886940).

1211983011801 is an frugal number, since it uses more digits than its factorization.

1211983011801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 733940 (or 366970 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 36.

Multiplying 1211983011801 by its sum of digits (36), we get a square (43631388424836 = 6605406²).

The spelling of 1211983011801 in words is "one trillion, two hundred eleven billion, nine hundred eighty-three million, eleven thousand, eight hundred one".