21603521016 has 360 divisors, whose sum is σ = 77383512360. Its totient is φ = 5610306240.

The previous prime is 21603520987. The next prime is 21603521021. The reversal of 21603521016 is 61012530612.

21603521016 is a `hidden beast` number, since 2 + 1 + 603 + 52 + 1 + 0 + 1 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 3839181 + ... + 3844803.

It is an arithmetic number, because the mean of its divisors is an integer number (214954201).

Almost surely, 2^21603521016 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 21603521016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38691756180).

21603521016 is an abundant number, since it is smaller than the sum of its proper divisors (55779991344).

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

21603521016 is a wasteful number, since it uses less digits than its factorization.

21603521016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5677 (or 5646 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The spelling of 21603521016 in words is "twenty-one billion, six hundred three million, five hundred twenty-one thousand, sixteen".