1221121015 has 4 divisors (see below), whose sum is σ = 1465345224. Its totient is φ = 976896808.

The previous prime is 1221121003. The next prime is 1221121021. The reversal of 1221121015 is 5101211221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5101211221 = 16273 ⋅313477.

It is a cyclic number.

It is not a de Polignac number, because 1221121015 - 2¹⁷ = 1220989943 is a prime.

It is a super-2 number, since 2×1221121015² = 2982273066549260450, which contains 22 as substring.

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 1221121015.

It is a congruent number.

It is an unprimeable number.

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, 122112097 + ... + 122112106.

It is an arithmetic number, because the mean of its divisors is an integer number (366336306).

Almost surely, 2^1221121015 is an apocalyptic number.

1221121015 is a deficient number, since it is larger than the sum of its proper divisors (244224209).

1221121015 is an equidigital number, since it uses as much as digits as its factorization.

1221121015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244224208.

The product of its (nonzero) digits is 40, while the sum is 16.

The square root of 1221121015 is about 34944.5419915614. The cubic root of 1221121015 is about 1068.8569080612.

Adding to 1221121015 its reverse (5101211221), we get a palindrome (6322332236).

The spelling of 1221121015 in words is "one billion, two hundred twenty-one million, one hundred twenty-one thousand, fifteen".