21221020001000 has 128 divisors (see below), whose sum is σ = 49838911200000. Its totient is φ = 8457368416000.

The previous prime is 21221020000963. The next prime is 21221020001017. The reversal of 21221020001000 is 10002012212.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 764735126 + ... + 764762874.

It is an arithmetic number, because the mean of its divisors is an integer number (389366493750).

Almost surely, 2^{21221020001000} is an apocalyptic number.

21221020001000 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 21221020001000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24919455600000).

21221020001000 is an abundant number, since it is smaller than the sum of its proper divisors (28617891199000).

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

21221020001000 is a wasteful number, since it uses less digits than its factorization.

21221020001000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30540 (or 30526 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21221020001000 its reverse (10002012212), we get a palindrome (21231022013212).

The spelling of 21221020001000 in words is "twenty-one trillion, two hundred twenty-one billion, twenty million, one thousand".