221221213021 has 8 divisors (see below), whose sum is σ = 221643191160. Its totient is φ = 220799324928.

The previous prime is 221221213009. The next prime is 221221213033. The reversal of 221221213021 is 120312122122.

It is an interprime number because it is at equal distance from previous prime (221221213009) and next prime (221221213033).

It can be written as a sum of positive squares in 4 ways, for example, as 35348136121 + 185873076900 = 188011^2 + 431130^2 .

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 221221213021 - 2¹³ = 221221204829 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 221221213021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221221213051) 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, 6877945 + ... + 6910033.

It is an arithmetic number, because the mean of its divisors is an integer number (27705398895).

Almost surely, 2^221221213021 is an apocalyptic number.

It is an amenable number.

221221213021 is a deficient number, since it is larger than the sum of its proper divisors (421978139).

221221213021 is a wasteful number, since it uses less digits than its factorization.

221221213021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45023.

The product of its (nonzero) digits is 192, while the sum is 19.

Adding to 221221213021 its reverse (120312122122), we get a palindrome (341533335143).

The spelling of 221221213021 in words is "two hundred twenty-one billion, two hundred twenty-one million, two hundred thirteen thousand, twenty-one".