1226399981 has 2 divisors, whose sum is σ = 1226399982. Its totient is φ = 1226399980.

The previous prime is 1226399939. The next prime is 1226400001. The reversal of 1226399981 is 1899936221.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1220104900 + 6295081 = 34930^2 + 2509^2 .

It is an emirp because it is prime and its reverse (1899936221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1226399981 - 2⁶ = 1226399917 is a prime.

It is a super-2 number, since 2×1226399981² = 3008113826793600722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1226399921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 613199990 + 613199991.

It is an arithmetic number, because the mean of its divisors is an integer number (613199991).

Almost surely, 2^1226399981 is an apocalyptic number.

It is an amenable number.

1226399981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1226399981 is an equidigital number, since it uses as much as digits as its factorization.

1226399981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 419904, while the sum is 50.

The square root of 1226399981 is about 35019.9940177037. The cubic root of 1226399981 is about 1070.3949341326.

The spelling of 1226399981 in words is "one billion, two hundred twenty-six million, three hundred ninety-nine thousand, nine hundred eighty-one".