21001213100 has 36 divisors (see below), whose sum is σ = 52083010224. Its totient is φ = 7200415680.

The previous prime is 21001213099. The next prime is 21001213117. The reversal of 21001213100 is 131210012.

It is a super-2 number, since 2×21001213100² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15000167 + ... + 15001566.

It is an arithmetic number, because the mean of its divisors is an integer number (1446750284).

Almost surely, 2^21001213100 is an apocalyptic number.

21001213100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001213100 is an abundant number, since it is smaller than the sum of its proper divisors (31081797124).

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

21001213100 is a wasteful number, since it uses less digits than its factorization.

21001213100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30001754 (or 30001747 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 11.

Adding to 21001213100 its reverse (131210012), we get a palindrome (21132423112).

The spelling of 21001213100 in words is "twenty-one billion, one million, two hundred thirteen thousand, one hundred".