1215908820 has 288 divisors, whose sum is σ = 4426426368. Its totient is φ = 274430592.

The previous prime is 1215908789. The next prime is 1215908821. The reversal of 1215908820 is 288095121.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1215908821) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 3503887 + ... + 3504233.

It is an arithmetic number, because the mean of its divisors is an integer number (15369536).

Almost surely, 2^1215908820 is an apocalyptic number.

1215908820 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 1215908820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2213213184).

1215908820 is an abundant number, since it is smaller than the sum of its proper divisors (3210517548).

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

1215908820 is a wasteful number, since it uses less digits than its factorization.

1215908820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481 (or 467 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 36.

The square root of 1215908820 is about 34869.8841409030. The cubic root of 1215908820 is about 1067.3339806572. Note that the first 3 decimals are identical.

The spelling of 1215908820 in words is "one billion, two hundred fifteen million, nine hundred eight thousand, eight hundred twenty".