21868308 has 180 divisors, whose sum is σ = 73408608. Its totient is φ = 5433120.

The previous prime is 21868303. The next prime is 21868321. The reversal of 21868308 is 80386812.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21868303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 950785 + ... + 950807.

Almost surely, 2^21868308 is an apocalyptic number.

21868308 is a gapful number since it is divisible by the number (28) 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 21868308, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36704304).

21868308 is an abundant number, since it is smaller than the sum of its proper divisors (51540300).

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

21868308 is a wasteful number, since it uses less digits than its factorization.

21868308 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 21868308 is about 4676.3562738525. The cubic root of 21868308 is about 279.6437135016.

The spelling of 21868308 in words is "twenty-one million, eight hundred sixty-eight thousand, three hundred eight".