1221515000 has 40 divisors (see below), whose sum is σ = 2862021360. Its totient is φ = 488604000.

The previous prime is 1221514993. The next prime is 1221515021. The reversal of 1221515000 is 5151221.

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 1221515000.

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 9 ways as a sum of consecutive naturals, for example, 117152 + ... + 127151.

It is an arithmetic number, because the mean of its divisors is an integer number (71550534).

Almost surely, 2^1221515000 is an apocalyptic number.

1221515000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221515000 is an abundant number, since it is smaller than the sum of its proper divisors (1640506360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221515000 is an equidigital number, since it uses as much as digits as its factorization.

1221515000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244329 (or 244310 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 1221515000 is about 34950.1788264381. The cubic root of 1221515000 is about 1068.9718484321.

Adding to 1221515000 its reverse (5151221), we get a palindrome (1226666221).

The spelling of 1221515000 in words is "one billion, two hundred twenty-one million, five hundred fifteen thousand".