1215351720 has 384 divisors, whose sum is σ = 4700592000. Its totient is φ = 269015040.

The previous prime is 1215351719. The next prime is 1215351733. The reversal of 1215351720 is 271535121.

1215351720 is a `hidden beast` number, since 121 + 5 + 3 + 517 + 20 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2181682 + ... + 2182238.

It is an arithmetic number, because the mean of its divisors is an integer number (12241125).

Almost surely, 2^1215351720 is an apocalyptic number.

1215351720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1215351720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2350296000).

1215351720 is an abundant number, since it is smaller than the sum of its proper divisors (3485240280).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1215351720 is a wasteful number, since it uses less digits than its factorization.

1215351720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 633 (or 626 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 27.

The square root of 1215351720 is about 34861.8949571018. The cubic root of 1215351720 is about 1067.1709468874.

Adding to 1215351720 its reverse (271535121), we get a palindrome (1486886841).

The spelling of 1215351720 in words is "one billion, two hundred fifteen million, three hundred fifty-one thousand, seven hundred twenty".