21381017580 has 480 divisors, whose sum is σ = 77475049344. Its totient is φ = 4894027776.

The previous prime is 21381017569. The next prime is 21381017591. The reversal of 21381017580 is 8571018312.

21381017580 is a `hidden beast` number, since 21 + 38 + 10 + 17 + 580 = 666.

It is an interprime number because it is at equal distance from previous prime (21381017569) and next prime (21381017591).

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

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, 17921464 + ... + 17922656.

Almost surely, 2^21381017580 is an apocalyptic number.

21381017580 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 21381017580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38737524672).

21381017580 is an abundant number, since it is smaller than the sum of its proper divisors (56094031764).

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

21381017580 is a wasteful number, since it uses less digits than its factorization.

21381017580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1287 (or 1276 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 36.

The spelling of 21381017580 in words is "twenty-one billion, three hundred eighty-one million, seventeen thousand, five hundred eighty".