1221506215 has 8 divisors (see below), whose sum is σ = 1468949040. Its totient is φ = 975110592.

The previous prime is 1221506207. The next prime is 1221506227. The reversal of 1221506215 is 5126051221.

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 1221506215 - 2³ = 1221506207 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221506215.

It is a congruent number.

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, 259230 + ... + 263899.

It is an arithmetic number, because the mean of its divisors is an integer number (183618630).

Almost surely, 2^1221506215 is an apocalyptic number.

1221506215 is a deficient number, since it is larger than the sum of its proper divisors (247442825).

1221506215 is an equidigital number, since it uses as much as digits as its factorization.

1221506215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523601.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 1221506215 is about 34950.0531473130. The cubic root of 1221506215 is about 1068.9692857838.

Adding to 1221506215 its reverse (5126051221), we get a palindrome (6347557436).

The spelling of 1221506215 in words is "one billion, two hundred twenty-one million, five hundred six thousand, two hundred fifteen".