21031100 has 36 divisors (see below), whose sum is σ = 48043800. Its totient is φ = 7968960.

The previous prime is 21031097. The next prime is 21031103. The reversal of 21031100 is 113012.

It is an interprime number because it is at equal distance from previous prime (21031097) and next prime (21031103).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3635 + ... + 7434.

It is an arithmetic number, because the mean of its divisors is an integer number (1334550).

Almost surely, 2^21031100 is an apocalyptic number.

21031100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21031100 is an abundant number, since it is smaller than the sum of its proper divisors (27012700).

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

21031100 is a wasteful number, since it uses less digits than its factorization.

21031100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11102 (or 11095 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 8.

The square root of 21031100 is about 4585.9677277539. The cubic root of 21031100 is about 276.0285449718.

Adding to 21031100 its reverse (113012), we get a palindrome (21144112).

The spelling of 21031100 in words is "twenty-one million, thirty-one thousand, one hundred".