21187795860 has 384 divisors, whose sum is σ = 83352084480. Its totient is φ = 4340044800.

The previous prime is 21187795859. The next prime is 21187795901. The reversal of 21187795860 is 6859778112.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 21187795797 and 21187795806.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2948592 + ... + 2955768.

It is an arithmetic number, because the mean of its divisors is an integer number (217062720).

Almost surely, 2^21187795860 is an apocalyptic number.

21187795860 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 21187795860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41676042240).

21187795860 is an abundant number, since it is smaller than the sum of its proper divisors (62164288620).

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

21187795860 is a wasteful number, since it uses less digits than its factorization.

21187795860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7284 (or 7276 counting only the distinct ones).

The product of its (nonzero) digits is 1693440, while the sum is 54.

The spelling of 21187795860 in words is "twenty-one billion, one hundred eighty-seven million, seven hundred ninety-five thousand, eight hundred sixty".