1221635123 has 2 divisors, whose sum is σ = 1221635124. Its totient is φ = 1221635122.

The previous prime is 1221635111. The next prime is 1221635131. The reversal of 1221635123 is 3215361221.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221635123 - 2¹² = 1221631027 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221635092 and 1221635101.

It is not a weakly prime, because it can be changed into another prime (1221635923) 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, 610817561 + 610817562.

It is an arithmetic number, because the mean of its divisors is an integer number (610817562).

Almost surely, 2^1221635123 is an apocalyptic number.

1221635123 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221635123 is an equidigital number, since it uses as much as digits as its factorization.

1221635123 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 26.

The square root of 1221635123 is about 34951.8972732526. The cubic root of 1221635123 is about 1069.0068879517.

Adding to 1221635123 its reverse (3215361221), we get a palindrome (4436996344).

The spelling of 1221635123 in words is "one billion, two hundred twenty-one million, six hundred thirty-five thousand, one hundred twenty-three".