21213108 has 36 divisors (see below), whose sum is σ = 61283040. Its totient is φ = 6060816.

The previous prime is 21213097. The next prime is 21213109. The reversal of 21213108 is 80131212.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213109) 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, 41838 + ... + 42341.

Almost surely, 2^21213108 is an apocalyptic number.

21213108 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21213108 is an abundant number, since it is smaller than the sum of its proper divisors (40069932).

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

21213108 is a wasteful number, since it uses less digits than its factorization.

21213108 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84196 (or 84191 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21213108 is about 4605.7689911675. The cubic root of 21213108 is about 276.8225305204.

It can be divided in two parts, 21213 and 108, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 21213108 in words is "twenty-one million, two hundred thirteen thousand, one hundred eight".