1221125515 has 8 divisors (see below), whose sum is σ = 1483899840. Its totient is φ = 964534272.

The previous prime is 1221125501. The next prime is 1221125599. The reversal of 1221125515 is 5155211221.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221125515 - 2⁵ = 1221125483 is a prime.

It is a super-2 number, since 2×1221125515² = 2982295046768030450, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221125515.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1545334 + ... + 1546123.

It is an arithmetic number, because the mean of its divisors is an integer number (185487480).

Almost surely, 2^1221125515 is an apocalyptic number.

1221125515 is a deficient number, since it is larger than the sum of its proper divisors (262774325).

1221125515 is an equidigital number, since it uses as much as digits as its factorization.

1221125515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3091541.

The product of its digits is 1000, while the sum is 25.

The square root of 1221125515 is about 34944.6063792397. The cubic root of 1221125515 is about 1068.8582210214.

Adding to 1221125515 its reverse (5155211221), we get a palindrome (6376336736).

It can be divided in two parts, 1221 and 125515, that added together give a square (126736 = 356²).

The spelling of 1221125515 in words is "one billion, two hundred twenty-one million, one hundred twenty-five thousand, five hundred fifteen".