1220001221981 has 2 divisors, whose sum is σ = 1220001221982. Its totient is φ = 1220001221980.

The previous prime is 1220001221977. The next prime is 1220001222017. The reversal of 1220001221981 is 1891221000221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1091260193956 + 128741028025 = 1044634^2 + 358805^2 .

It is a cyclic number.

It is not a de Polignac number, because 1220001221981 - 2² = 1220001221977 is a prime.

It is a super-2 number, since 2×1220001221981² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1220001221911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610000610990 + 610000610991.

It is an arithmetic number, because the mean of its divisors is an integer number (610000610991).

Almost surely, 2^{1220001221981} is an apocalyptic number.

It is an amenable number.

1220001221981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1220001221981 is an equidigital number, since it uses as much as digits as its factorization.

1220001221981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 29.

The spelling of 1220001221981 in words is "one trillion, two hundred twenty billion, one million, two hundred twenty-one thousand, nine hundred eighty-one".