21011211000 has 512 divisors, whose sum is σ = 81014169600. Its totient is φ = 5002560000.

The previous prime is 21011210963. The next prime is 21011211017. The reversal of 21011211000 is 11211012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 10880035 + ... + 10881965.

It is an arithmetic number, because the mean of its divisors is an integer number (158230800).

Almost surely, 2^21011211000 is an apocalyptic number.

21011211000 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 21011211000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40507084800).

21011211000 is an abundant number, since it is smaller than the sum of its proper divisors (60002958600).

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

21011211000 is a wasteful number, since it uses less digits than its factorization.

21011211000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2005 (or 1985 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21011211000 its reverse (11211012), we get a palindrome (21022422012).

The spelling of 21011211000 in words is "twenty-one billion, eleven million, two hundred eleven thousand".