21705088860 has 480 divisors, whose sum is σ = 86709490560. Its totient is φ = 4420749312.

The previous prime is 21705088859. The next prime is 21705088879. The reversal of 21705088860 is 6888050712.

21705088860 is a `hidden beast` number, since 2 + 1 + 7 + 0 + 508 + 88 + 60 = 666.

It is a super-2 number, since 2×21705088860² (a number of 21 digits) contains 22 as substring.

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 159 ways as a sum of consecutive naturals, for example, 4272642 + ... + 4277718.

It is an arithmetic number, because the mean of its divisors is an integer number (180644772).

Almost surely, 2^21705088860 is an apocalyptic number.

21705088860 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 21705088860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43354745280).

21705088860 is an abundant number, since it is smaller than the sum of its proper divisors (65004401700).

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

21705088860 is a wasteful number, since it uses less digits than its factorization.

21705088860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5147 (or 5136 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 21705088860 in words is "twenty-one billion, seven hundred five million, eighty-eight thousand, eight hundred sixty".