1221801505 has 4 divisors (see below), whose sum is σ = 1466161812. Its totient is φ = 977441200.

The previous prime is 1221801487. The next prime is 1221801541. The reversal of 1221801505 is 5051081221.

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

It can be written as a sum of positive squares in 2 ways, for example, as 426505104 + 795296401 = 20652^2 + 28201^2 .

It is not a de Polignac number, because 1221801505 - 2⁵ = 1221801473 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221801505.

It is an unprimeable number.

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, 122180146 + ... + 122180155.

It is an arithmetic number, because the mean of its divisors is an integer number (366540453).

Almost surely, 2^1221801505 is an apocalyptic number.

It is an amenable number.

1221801505 is a deficient number, since it is larger than the sum of its proper divisors (244360307).

1221801505 is an equidigital number, since it uses as much as digits as its factorization.

1221801505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244360306.

The product of its (nonzero) digits is 800, while the sum is 25.

The square root of 1221801505 is about 34954.2773491314. The cubic root of 1221801505 is about 1069.0554172893.

Adding to 1221801505 its reverse (5051081221), we get a palindrome (6272882726).

The spelling of 1221801505 in words is "one billion, two hundred twenty-one million, eight hundred one thousand, five hundred five".