1215731721600 has 2016 divisors, whose sum is σ = 5102190235800. Its totient is φ = 285758668800.

The previous prime is 1215731721593. The next prime is 1215731721601. The reversal of 1215731721600 is 61271375121.

1215731721600 is a `hidden beast` number, since 1 + 2 + 1 + 573 + 1 + 7 + 21 + 60 + 0 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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 (1215731721601) by changing a digit.

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 251 ways as a sum of consecutive naturals, for example, 16653859164 + ... + 16653859236.

Almost surely, 2^{1215731721600} is an apocalyptic number.

1215731721600 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 1215731721600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2551095117900).

1215731721600 is an abundant number, since it is smaller than the sum of its proper divisors (3886458514200).

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

1215731721600 is an equidigital number, since it uses as much as digits as its factorization.

1215731721600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 153 counting only the distinct ones).

The product of its (nonzero) digits is 17640, while the sum is 36.

The spelling of 1215731721600 in words is "one trillion, two hundred fifteen billion, seven hundred thirty-one million, seven hundred twenty-one thousand, six hundred".