221020001261 has 2 divisors, whose sum is σ = 221020001262. Its totient is φ = 221020001260.

The previous prime is 221020001203. The next prime is 221020001269. The reversal of 221020001261 is 162100020122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 182270078761 + 38749922500 = 426931^2 + 196850^2 .

It is a cyclic number.

It is not a de Polignac number, because 221020001261 - 2¹⁸ = 221019739117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221020001269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110510000630 + 110510000631.

It is an arithmetic number, because the mean of its divisors is an integer number (110510000631).

Almost surely, 2^221020001261 is an apocalyptic number.

It is an amenable number.

221020001261 is a deficient number, since it is larger than the sum of its proper divisors (1).

221020001261 is an equidigital number, since it uses as much as digits as its factorization.

221020001261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 221020001261 its reverse (162100020122), we get a palindrome (383120021383).

The spelling of 221020001261 in words is "two hundred twenty-one billion, twenty million, one thousand, two hundred sixty-one".