21055001000 has 128 divisors (see below), whose sum is σ = 54430272000. Its totient is φ = 7559136000.

The previous prime is 21055000987. The next prime is 21055001039. The reversal of 21055001000 is 10055012.

It is a super-2 number, since 2×21055001000² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 856886 + ... + 881114.

It is an arithmetic number, because the mean of its divisors is an integer number (425236500).

Almost surely, 2^21055001000 is an apocalyptic number.

21055001000 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 21055001000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27215136000).

21055001000 is an abundant number, since it is smaller than the sum of its proper divisors (33375271000).

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

21055001000 is a wasteful number, since it uses less digits than its factorization.

21055001000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24340 (or 24326 counting only the distinct ones).

The product of its (nonzero) digits is 50, while the sum is 14.

Adding to 21055001000 its reverse (10055012), we get a palindrome (21065056012).

The spelling of 21055001000 in words is "twenty-one billion, fifty-five million, one thousand".