1221545303961 has 4 divisors (see below), whose sum is σ = 1628727071952. Its totient is φ = 814363535972.

The previous prime is 1221545303917. The next prime is 1221545303963. The reversal of 1221545303961 is 1693035451221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221545303961 - 2¹⁹ = 1221544779673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221545303963) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203590883991 + ... + 203590883996.

It is an arithmetic number, because the mean of its divisors is an integer number (407181767988).

Almost surely, 2^{1221545303961} is an apocalyptic number.

It is an amenable number.

1221545303961 is a deficient number, since it is larger than the sum of its proper divisors (407181767991).

1221545303961 is an equidigital number, since it uses as much as digits as its factorization.

1221545303961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407181767990.

The product of its (nonzero) digits is 194400, while the sum is 42.

The spelling of 1221545303961 in words is "one trillion, two hundred twenty-one billion, five hundred forty-five million, three hundred three thousand, nine hundred sixty-one".