21010001000 has 64 divisors (see below), whose sum is σ = 49186809360. Its totient is φ = 8400000000.

The previous prime is 21010000967. The next prime is 21010001011. The reversal of 21010001000 is 10001012.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 532963396 + 20477037604 = 23086^2 + 143098^2 .

It is a Harshad number since it is a multiple of its sum of digits (5).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2997500 + ... + 3004500.

Almost surely, 2^21010001000 is an apocalyptic number.

21010001000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21010001000 is an abundant number, since it is smaller than the sum of its proper divisors (28176808360).

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

21010001000 is a wasteful number, since it uses less digits than its factorization.

21010001000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10023 (or 10009 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 5.

Adding to 21010001000 its reverse (10001012), we get a palindrome (21020002012).

The spelling of 21010001000 in words is "twenty-one billion, ten million, one thousand".