1221516455 has 4 divisors (see below), whose sum is σ = 1465819752. Its totient is φ = 977213160.

The previous prime is 1221516451. The next prime is 1221516503. The reversal of 1221516455 is 5546151221.

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

It is not a de Polignac number, because 1221516455 - 2² = 1221516451 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221516451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122151641 + ... + 122151650.

It is an arithmetic number, because the mean of its divisors is an integer number (366454938).

Almost surely, 2^1221516455 is an apocalyptic number.

1221516455 is a deficient number, since it is larger than the sum of its proper divisors (244303297).

1221516455 is an equidigital number, since it uses as much as digits as its factorization.

1221516455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244303296.

The product of its digits is 12000, while the sum is 32.

The square root of 1221516455 is about 34950.1996417760. The cubic root of 1221516455 is about 1068.9722728650.

Adding to 1221516455 its reverse (5546151221), we get a palindrome (6767667676).

The spelling of 1221516455 in words is "one billion, two hundred twenty-one million, five hundred sixteen thousand, four hundred fifty-five".