1231211220021 has 24 divisors (see below), whose sum is σ = 1883283390144. Its totient is φ = 772420291200.

The previous prime is 1231211220017. The next prime is 1231211220067. The reversal of 1231211220021 is 1200221121321.

1231211220021 is a `hidden beast` number, since 1 + 231 + 211 + 2 + 200 + 21 = 666.

It is not a de Polignac number, because 1231211220021 - 2² = 1231211220017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1231211219976 and 1231211220003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231211220011) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 600000 + ... + 1680006.

It is an arithmetic number, because the mean of its divisors is an integer number (78470141256).

Almost surely, 2^{1231211220021} is an apocalyptic number.

It is an amenable number.

1231211220021 is a deficient number, since it is larger than the sum of its proper divisors (652072170123).

1231211220021 is a wasteful number, since it uses less digits than its factorization.

1231211220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1087481 (or 1087478 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

Adding to 1231211220021 its reverse (1200221121321), we get a palindrome (2431432341342).

The spelling of 1231211220021 in words is "one trillion, two hundred thirty-one billion, two hundred eleven million, two hundred twenty thousand, twenty-one".