1021220221 has 6 divisors (see below), whose sum is σ = 1187950110. Its totient is φ = 875331576.

The previous prime is 1021220143. The next prime is 1021220257. The reversal of 1021220221 is 1220221201.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 756800100 + 264420121 = 27510^2 + 16261^2 .

It is not a de Polignac number, because 1021220221 - 2⁹ = 1021219709 is a prime.

It is a super-3 number, since 3×1021220221³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021220021) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10420566 + ... + 10420663.

It is an arithmetic number, because the mean of its divisors is an integer number (197991685).

Almost surely, 2^1021220221 is an apocalyptic number.

It is an amenable number.

1021220221 is a deficient number, since it is larger than the sum of its proper divisors (166729889).

1021220221 is an equidigital number, since it uses as much as digits as its factorization.

1021220221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20841243 (or 20841236 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 1021220221 is about 31956.5364362285. The cubic root of 1021220221 is about 1007.0239555374.

Adding to 1021220221 its reverse (1220221201), we get a palindrome (2241441422).

The spelling of 1021220221 in words is "one billion, twenty-one million, two hundred twenty thousand, two hundred twenty-one".