221020100001 has 24 divisors (see below), whose sum is σ = 338049939240. Its totient is φ = 138671402496.

The previous prime is 221020099999. The next prime is 221020100009. The reversal of 221020100001 is 100001020122.

It can be written as a sum of positive squares in 4 ways, for example, as 117385038225 + 103635061776 = 342615^2 + 321924^2 .

It is not a de Polignac number, because 221020100001 - 2¹ = 221020099999 is a prime.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221020100009) 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, 3886891 + ... + 3943343.

It is an arithmetic number, because the mean of its divisors is an integer number (14085414135).

Almost surely, 2^221020100001 is an apocalyptic number.

It is an amenable number.

221020100001 is a deficient number, since it is larger than the sum of its proper divisors (117029839239).

221020100001 is a wasteful number, since it uses less digits than its factorization.

221020100001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82065 (or 82062 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 221020100001 its reverse (100001020122), we get a palindrome (321021120123).

The spelling of 221020100001 in words is "two hundred twenty-one billion, twenty million, one hundred thousand, one".