21001222000 has 320 divisors, whose sum is σ = 59152249728. Its totient is φ = 7127040000.

The previous prime is 21001221953. The next prime is 21001222009. The reversal of 21001222000 is 22210012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001222009) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 87141880 + ... + 87142120.

Almost surely, 2^21001222000 is an apocalyptic number.

21001222000 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 21001222000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29576124864).

21001222000 is an abundant number, since it is smaller than the sum of its proper divisors (38151027728).

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

21001222000 is a wasteful number, since it uses less digits than its factorization.

21001222000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525 (or 509 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21001222000 its reverse (22210012), we get a palindrome (21023432012).

The spelling of 21001222000 in words is "twenty-one billion, one million, two hundred twenty-two thousand".