221221001221021 has 8 divisors (see below), whose sum is σ = 222016715611704. Its totient is φ = 220425346767360.

The previous prime is 221221001220931. The next prime is 221221001221061. The reversal of 221221001221021 is 120122100122122.

221221001221021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 159459792252121 + 61761208968900 = 12627739^2 + 7858830^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221221001221021 - 2²⁷ = 221220867003293 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221221001221021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221221001221061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7582636 + ... + 22359301.

It is an arithmetic number, because the mean of its divisors is an integer number (27752089451463).

Almost surely, 2^{221221001221021} is an apocalyptic number.

It is an amenable number.

221221001221021 is a deficient number, since it is larger than the sum of its proper divisors (795714390683).

221221001221021 is a wasteful number, since it uses less digits than its factorization.

221221001221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29968511.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 221221001221021 its reverse (120122100122122), we get a palindrome (341343101343143).

The spelling of 221221001221021 in words is "two hundred twenty-one trillion, two hundred twenty-one billion, one million, two hundred twenty-one thousand, twenty-one".