1221010081 has 2 divisors, whose sum is σ = 1221010082. Its totient is φ = 1221010080.

The previous prime is 1221010079. The next prime is 1221010097. The reversal of 1221010081 is 1800101221.

It is an a-pointer prime, because the next prime (1221010097) can be obtained adding 1221010081 to its sum of digits (16).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1182259456 + 38750625 = 34384^2 + 6225^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221010081 - 2¹ = 1221010079 is a prime.

It is a super-2 number, since 2×1221010081² = 2981731235807253122, which contains 22 as substring.

Together with 1221010079, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1221010181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610505040 + 610505041.

It is an arithmetic number, because the mean of its divisors is an integer number (610505041).

Almost surely, 2^1221010081 is an apocalyptic number.

It is an amenable number.

1221010081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221010081 is an equidigital number, since it uses as much as digits as its factorization.

1221010081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 16.

The square root of 1221010081 is about 34942.9546690030. The cubic root of 1221010081 is about 1068.8245399443.

The spelling of 1221010081 in words is "one billion, two hundred twenty-one million, ten thousand, eighty-one".