1221666931 has 2 divisors, whose sum is σ = 1221666932. Its totient is φ = 1221666930.

The previous prime is 1221666923. The next prime is 1221666983. The reversal of 1221666931 is 1396661221.

It is a weak prime.

It is an emirp because it is prime and its reverse (1396661221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221666931 - 2³ = 1221666923 is a prime.

It is a super-2 number, since 2×1221666931² = 2984940180597917522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1221666991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610833465 + 610833466.

It is an arithmetic number, because the mean of its divisors is an integer number (610833466).

Almost surely, 2^1221666931 is an apocalyptic number.

1221666931 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221666931 is an equidigital number, since it uses as much as digits as its factorization.

1221666931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 37.

The square root of 1221666931 is about 34952.3522956610. The cubic root of 1221666931 is about 1069.0161658655.

The spelling of 1221666931 in words is "one billion, two hundred twenty-one million, six hundred sixty-six thousand, nine hundred thirty-one".