21203100 has 72 divisors (see below), whose sum is σ = 68172720. Its totient is φ = 5653440.

The previous prime is 21203099. The next prime is 21203113. The reversal of 21203100 is 130212.

It is a happy number.

It is a super-2 number, since 2×21203100² = 899142899220000, which contains 22 as substring.

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 23 ways as a sum of consecutive naturals, for example, 1227 + ... + 6626.

Almost surely, 2^21203100 is an apocalyptic number.

21203100 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 21203100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34086360).

21203100 is an abundant number, since it is smaller than the sum of its proper divisors (46969620).

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

21203100 is a wasteful number, since it uses less digits than its factorization.

21203100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7876 (or 7863 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21203100 is about 4604.6823994712. The cubic root of 21203100 is about 276.7789902137.

Adding to 21203100 its reverse (130212), we get a palindrome (21333312).

The spelling of 21203100 in words is "twenty-one million, two hundred three thousand, one hundred".