1216215515 has 4 divisors (see below), whose sum is σ = 1459458624. Its totient is φ = 972972408.

The previous prime is 1216215509. The next prime is 1216215521. The reversal of 1216215515 is 5155126121.

1216215515 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1216215509) and next prime (1216215521).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1216215515 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121621547 + ... + 121621556.

It is an arithmetic number, because the mean of its divisors is an integer number (364864656).

Almost surely, 2^1216215515 is an apocalyptic number.

1216215515 is a deficient number, since it is larger than the sum of its proper divisors (243243109).

1216215515 is an equidigital number, since it uses as much as digits as its factorization.

1216215515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243243108.

The product of its digits is 3000, while the sum is 29.

The square root of 1216215515 is about 34874.2815696610. The cubic root of 1216215515 is about 1067.4237128452.

The spelling of 1216215515 in words is "one billion, two hundred sixteen million, two hundred fifteen thousand, five hundred fifteen".