21007215171072 has 320 divisors, whose sum is σ = 67409680504320. Its totient is φ = 6420943872000.

The previous prime is 21007215171071. The next prime is 21007215171077. The reversal of 21007215171072 is 27017151270012.

It is a happy number.

21007215171072 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 72 + 1 + 517 + 1 + 0 + 72 = 666.

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 (21007215171071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26749447 + ... + 27523577.

It is an arithmetic number, because the mean of its divisors is an integer number (210655251576).

Almost surely, 2^{21007215171072} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21007215171072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33704840252160).

21007215171072 is an abundant number, since it is smaller than the sum of its proper divisors (46402465333248).

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

21007215171072 is a wasteful number, since it uses less digits than its factorization.

21007215171072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 774322 (or 774300 counting only the distinct ones).

The product of its (nonzero) digits is 13720, while the sum is 36.

The spelling of 21007215171072 in words is "twenty-one trillion, seven billion, two hundred fifteen million, one hundred seventy-one thousand, seventy-two".