21012100 has 36 divisors (see below), whose sum is σ = 48000400. Its totient is φ = 7961760.

The previous prime is 21012091. The next prime is 21012127. The reversal of 21012100 is 121012.

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, 3630 + ... + 7429.

Almost surely, 2^21012100 is an apocalyptic number.

21012100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012100 is an abundant number, since it is smaller than the sum of its proper divisors (26988300).

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

21012100 is a wasteful number, since it uses less digits than its factorization.

21012100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11092 (or 11085 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21012100 is about 4583.8957230722. The cubic root of 21012100 is about 275.9453963253.

Adding to 21012100 its reverse (121012), we get a palindrome (21133112).

It can be divided in two parts, 21012 and 100, that added together give a palindrome (21112).

The spelling of 21012100 in words is "twenty-one million, twelve thousand, one hundred".