221020001 has 2 divisors, whose sum is σ = 221020002. Its totient is φ = 221020000.

The previous prime is 221019961. The next prime is 221020003. The reversal of 221020001 is 100020122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 121000000 + 100020001 = 11000^2 + 10001^2 .

It is a cyclic number.

It is not a de Polignac number, because 221020001 - 2⁶ = 221019937 is a prime.

Together with 221020003, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221020003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110510000 + 110510001.

It is an arithmetic number, because the mean of its divisors is an integer number (110510001).

Almost surely, 2^221020001 is an apocalyptic number.

It is an amenable number.

221020001 is a deficient number, since it is larger than the sum of its proper divisors (1).

221020001 is an equidigital number, since it uses as much as digits as its factorization.

221020001 is an evil number, because the sum of its binary digits is even.

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

The square root of 221020001 is about 14866.7414385265. The cubic root of 221020001 is about 604.6125981035.

Adding to 221020001 its reverse (100020122), we get a palindrome (321040123).

The spelling of 221020001 in words is "two hundred twenty-one million, twenty thousand, one".