1221450320251 has 4 divisors (see below), whose sum is σ = 1395943223152. Its totient is φ = 1046957417352.

The previous prime is 1221450320231. The next prime is 1221450320273. The reversal of 1221450320251 is 1520230541221.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1221450320251 - 2³⁹ = 671694506363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221450320231) 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, 87246451440 + ... + 87246451453.

It is an arithmetic number, because the mean of its divisors is an integer number (348985805788).

Almost surely, 2^{1221450320251} is an apocalyptic number.

1221450320251 is a deficient number, since it is larger than the sum of its proper divisors (174492902901).

1221450320251 is an equidigital number, since it uses as much as digits as its factorization.

1221450320251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174492902900.

The product of its (nonzero) digits is 4800, while the sum is 28.

Adding to 1221450320251 its reverse (1520230541221), we get a palindrome (2741680861472).

The spelling of 1221450320251 in words is "one trillion, two hundred twenty-one billion, four hundred fifty million, three hundred twenty thousand, two hundred fifty-one".