21851641500 has 192 divisors, whose sum is σ = 68897267712. Its totient is φ = 5349792000.

The previous prime is 21851641453. The next prime is 21851641531. The reversal of 21851641500 is 514615812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3721567 + ... + 3727433.

It is an arithmetic number, because the mean of its divisors is an integer number (358839936).

Almost surely, 2^21851641500 is an apocalyptic number.

21851641500 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 21851641500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34448633856).

21851641500 is an abundant number, since it is smaller than the sum of its proper divisors (47045626212).

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

21851641500 is a wasteful number, since it uses less digits than its factorization.

21851641500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6093 (or 6081 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 33.

The spelling of 21851641500 in words is "twenty-one billion, eight hundred fifty-one million, six hundred forty-one thousand, five hundred".