21905878500 has 576 divisors, whose sum is σ = 80068165632. Its totient is φ = 4989600000.

The previous prime is 21905878481. The next prime is 21905878507. The reversal of 21905878500 is 587850912.

It is a happy number.

21905878500 is a `hidden beast` number, since 2 + 1 + 90 + 58 + 7 + 8 + 500 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21905878507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 80833365 + ... + 80833635.

It is an arithmetic number, because the mean of its divisors is an integer number (139007232).

Almost surely, 2^21905878500 is an apocalyptic number.

21905878500 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 21905878500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40034082816).

21905878500 is an abundant number, since it is smaller than the sum of its proper divisors (58162287132).

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

21905878500 is a wasteful number, since it uses less digits than its factorization.

21905878500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401 (or 386 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 45.

The spelling of 21905878500 in words is "twenty-one billion, nine hundred five million, eight hundred seventy-eight thousand, five hundred".