221221001001 has 128 divisors (see below), whose sum is σ = 428146790400. Its totient is φ = 97779778560.

The previous prime is 221221000997. The next prime is 221221001009. The reversal of 221221001001 is 100100122122.

It is not a de Polignac number, because 221221001001 - 2² = 221221000997 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221221001009) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2058715 + ... + 2163503.

It is an arithmetic number, because the mean of its divisors is an integer number (3344896800).

Almost surely, 2^221221001001 is an apocalyptic number.

221221001001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

221221001001 is a deficient number, since it is larger than the sum of its proper divisors (206925789399).

221221001001 is a wasteful number, since it uses less digits than its factorization.

221221001001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104879.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 221221001001 its reverse (100100122122), we get a palindrome (321321123123).

It can be divided in two parts, 22122 and 1001001, that multiplied together give a palindrome (22144144122).

The spelling of 221221001001 in words is "two hundred twenty-one billion, two hundred twenty-one million, one thousand, one".