21001032100 has 36 divisors (see below), whose sum is σ = 45673834500. Its totient is φ = 8381685760.

The previous prime is 21001032097. The next prime is 21001032103. The reversal of 21001032100 is 123010012.

It is an interprime number because it is at equal distance from previous prime (21001032097) and next prime (21001032103).

It can be written as a sum of positive squares in 6 ways, for example, as 827943076 + 20173089024 = 28774^2 + 142032^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21001032103) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 188965 + ... + 278764.

It is an arithmetic number, because the mean of its divisors is an integer number (1268717625).

Almost surely, 2^21001032100 is an apocalyptic number.

21001032100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001032100 is an abundant number, since it is smaller than the sum of its proper divisors (24672802400).

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

21001032100 is a wasteful number, since it uses less digits than its factorization.

21001032100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 468192 (or 468185 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21001032100 its reverse (123010012), we get a palindrome (21124042112).

The spelling of 21001032100 in words is "twenty-one billion, one million, thirty-two thousand, one hundred".