21535740072 has 192 divisors, whose sum is σ = 72856143360. Its totient is φ = 5583081600.

The previous prime is 21535740041. The next prime is 21535740091. The reversal of 21535740072 is 27004753512.

21535740072 is a `hidden beast` number, since 2 + 15 + 3 + 574 + 0 + 0 + 72 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3162223 + ... + 3169025.

It is an arithmetic number, because the mean of its divisors is an integer number (379459080).

Almost surely, 2^21535740072 is an apocalyptic number.

21535740072 is a gapful number since it is divisible by the number (22) 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 21535740072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36428071680).

21535740072 is an abundant number, since it is smaller than the sum of its proper divisors (51320403288).

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

21535740072 is a wasteful number, since it uses less digits than its factorization.

21535740072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7404 (or 7397 counting only the distinct ones).

The product of its (nonzero) digits is 58800, while the sum is 36.

The spelling of 21535740072 in words is "twenty-one billion, five hundred thirty-five million, seven hundred forty thousand, seventy-two".