21020001000 has 64 divisors (see below), whose sum is σ = 65582412480. Its totient is φ = 5605332800.

The previous prime is 21020000927. The next prime is 21020001071. The reversal of 21020001000 is 10002012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21020001000.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 3500334 + ... + 3506333.

It is an arithmetic number, because the mean of its divisors is an integer number (1024725195).

Almost surely, 2^21020001000 is an apocalyptic number.

21020001000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020001000 is an abundant number, since it is smaller than the sum of its proper divisors (44562411480).

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

21020001000 is a wasteful number, since it uses less digits than its factorization.

21020001000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7006691 (or 7006677 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 6.

Adding to 21020001000 its reverse (10002012), we get a palindrome (21030003012).

The spelling of 21020001000 in words is "twenty-one billion, twenty million, one thousand".