1221011215 has 16 divisors (see below), whose sum is σ = 1519627680. Its totient is φ = 940705920.

The previous prime is 1221011177. The next prime is 1221011221. The reversal of 1221011215 is 5121101221.

It is not a de Polignac number, because 1221011215 - 2²¹ = 1218914063 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46960 + ... + 68170.

It is an arithmetic number, because the mean of its divisors is an integer number (94976730).

Almost surely, 2^1221011215 is an apocalyptic number.

1221011215 is a deficient number, since it is larger than the sum of its proper divisors (298616465).

1221011215 is a wasteful number, since it uses less digits than its factorization.

1221011215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21642.

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

The square root of 1221011215 is about 34942.9708954462. The cubic root of 1221011215 is about 1068.8248708307.

Adding to 1221011215 its reverse (5121101221), we get a palindrome (6342112436).

The spelling of 1221011215 in words is "one billion, two hundred twenty-one million, eleven thousand, two hundred fifteen".