21525640560 has 120 divisors (see below), whose sum is σ = 72360487680. Its totient is φ = 5734596096.

The previous prime is 21525640541. The next prime is 21525640583. The reversal of 21525640560 is 6504652512.

21525640560 is a `hidden beast` number, since 2 + 1 + 5 + 2 + 5 + 640 + 5 + 6 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×21525640560² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 755697 + ... + 783663.

It is an arithmetic number, because the mean of its divisors is an integer number (603004064).

Almost surely, 2^21525640560 is an apocalyptic number.

21525640560 is a gapful number since it is divisible by the number (20) 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 21525640560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36180243840).

21525640560 is an abundant number, since it is smaller than the sum of its proper divisors (50834847120).

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

21525640560 is a wasteful number, since it uses less digits than its factorization.

21525640560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29055 (or 29046 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 36.

The spelling of 21525640560 in words is "twenty-one billion, five hundred twenty-five million, six hundred forty thousand, five hundred sixty".