1215501555 has 16 divisors (see below), whose sum is σ = 1976685984. Its totient is φ = 637639680.

The previous prime is 1215501533. The next prime is 1215501571. The reversal of 1215501555 is 5551055121.

It is not a de Polignac number, because 1215501555 - 2²⁰ = 1214452979 is a prime.

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, 663294 + ... + 665123.

It is an arithmetic number, because the mean of its divisors is an integer number (123542874).

Almost surely, 2^1215501555 is an apocalyptic number.

1215501555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1215501555 is a deficient number, since it is larger than the sum of its proper divisors (761184429).

1215501555 is a wasteful number, since it uses less digits than its factorization.

1215501555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1328486.

The product of its (nonzero) digits is 6250, while the sum is 30.

The square root of 1215501555 is about 34864.0438704405. The cubic root of 1215501555 is about 1067.2148005817.

Adding to 1215501555 its reverse (5551055121), we get a palindrome (6766556676).

The spelling of 1215501555 in words is "one billion, two hundred fifteen million, five hundred one thousand, five hundred fifty-five".