21861826560 has 544 divisors, whose sum is σ = 89086337280. Its totient is φ = 4982833152.

The previous prime is 21861826559. The next prime is 21861826579. The reversal of 21861826560 is 6562816812.

21861826560 is a `hidden beast` number, since 2 + 1 + 8 + 6 + 1 + 82 + 6 + 560 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 61931344 + ... + 61931696.

Almost surely, 2^21861826560 is an apocalyptic number.

21861826560 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 21861826560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44543168640).

21861826560 is an abundant number, since it is smaller than the sum of its proper divisors (67224510720).

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

21861826560 is an frugal number, since it uses more digits than its factorization.

21861826560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406 (or 370 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The spelling of 21861826560 in words is "twenty-one billion, eight hundred sixty-one million, eight hundred twenty-six thousand, five hundred sixty".