1221253215 has 192 divisors, whose sum is σ = 2669184000. Its totient is φ = 472469760.

The previous prime is 1221253211. The next prime is 1221253343. The reversal of 1221253215 is 5123521221.

1221253215 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1221253215 - 2² = 1221253211 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221253211) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 39395250 + ... + 39395280.

It is an arithmetic number, because the mean of its divisors is an integer number (13902000).

Almost surely, 2^1221253215 is an apocalyptic number.

1221253215 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1221253215 is an abundant number, since it is smaller than the sum of its proper divisors (1447930785).

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

1221253215 is a wasteful number, since it uses less digits than its factorization.

1221253215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123 (or 78 counting only the distinct ones).

The product of its digits is 1200, while the sum is 24.

The square root of 1221253215 is about 34946.4335090149. The cubic root of 1221253215 is about 1068.8954785721.

Adding to 1221253215 its reverse (5123521221), we get a palindrome (6344774436).

The spelling of 1221253215 in words is "one billion, two hundred twenty-one million, two hundred fifty-three thousand, two hundred fifteen".