1215001555 has 4 divisors (see below), whose sum is σ = 1458001872. Its totient is φ = 972001240.

The previous prime is 1215001549. The next prime is 1215001591. The reversal of 1215001555 is 5551005121.

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

It is not a de Polignac number, because 1215001555 - 2²⁵ = 1181447123 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121500151 + ... + 121500160.

It is an arithmetic number, because the mean of its divisors is an integer number (364500468).

Almost surely, 2^1215001555 is an apocalyptic number.

1215001555 is a deficient number, since it is larger than the sum of its proper divisors (243000317).

1215001555 is an equidigital number, since it uses as much as digits as its factorization.

1215001555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243000316.

The product of its (nonzero) digits is 1250, while the sum is 25.

The square root of 1215001555 is about 34856.8724213748. The cubic root of 1215001555 is about 1067.0684465706.

Adding to 1215001555 its reverse (5551005121), we get a palindrome (6766006676).

The spelling of 1215001555 in words is "one billion, two hundred fifteen million, one thousand, five hundred fifty-five".