1221663523 has 4 divisors (see below), whose sum is σ = 1222291648. Its totient is φ = 1221035400.

The previous prime is 1221663491. The next prime is 1221663529. The reversal of 1221663523 is 3253661221.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3253661221 = 719 ⋅4525259.

It is a cyclic number.

It is not a de Polignac number, because 1221663523 - 2⁵ = 1221663491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221663529) 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 in 3 ways as a sum of consecutive naturals, for example, 311136 + ... + 315037.

It is an arithmetic number, because the mean of its divisors is an integer number (305572912).

Almost surely, 2^1221663523 is an apocalyptic number.

1221663523 is a deficient number, since it is larger than the sum of its proper divisors (628125).

1221663523 is an equidigital number, since it uses as much as digits as its factorization.

1221663523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 628124.

The product of its digits is 12960, while the sum is 31.

The square root of 1221663523 is about 34952.3035435434. The cubic root of 1221663523 is about 1069.0151718110.

The spelling of 1221663523 in words is "one billion, two hundred twenty-one million, six hundred sixty-three thousand, five hundred twenty-three".