1221555315515 has 8 divisors (see below), whose sum is σ = 1465995928608. Its totient is φ = 977157885760.

The previous prime is 1221555315511. The next prime is 1221555315577. The reversal of 1221555315515 is 5155135551221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1221555315515 - 2² = 1221555315511 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221555315511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10733567 + ... + 10846776.

It is an arithmetic number, because the mean of its divisors is an integer number (183249491076).

Almost surely, 2^{1221555315515} is an apocalyptic number.

1221555315515 is a deficient number, since it is larger than the sum of its proper divisors (244440613093).

1221555315515 is a wasteful number, since it uses less digits than its factorization.

1221555315515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21591669.

The product of its digits is 187500, while the sum is 41.

The spelling of 1221555315515 in words is "one trillion, two hundred twenty-one billion, five hundred fifty-five million, three hundred fifteen thousand, five hundred fifteen".