21601866000 has 640 divisors, whose sum is σ = 86691451392. Its totient is φ = 4546560000.

The previous prime is 21601865959. The next prime is 21601866043. The reversal of 21601866000 is 66810612.

It is a super-2 number, since 2×21601866000² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 14585260 + ... + 14586740.

Almost surely, 2^21601866000 is an apocalyptic number.

21601866000 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 21601866000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43345725696).

21601866000 is an abundant number, since it is smaller than the sum of its proper divisors (65089585392).

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

21601866000 is a wasteful number, since it uses less digits than its factorization.

21601866000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1548 (or 1532 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The spelling of 21601866000 in words is "twenty-one billion, six hundred one million, eight hundred sixty-six thousand".