21313888 has 36 divisors (see below), whose sum is σ = 42899220. Its totient is φ = 10423680.

The previous prime is 21313867. The next prime is 21313909. The reversal of 21313888 is 88831312.

It is an interprime number because it is at equal distance from previous prime (21313867) and next prime (21313909).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 118983 + ... + 119161.

It is an arithmetic number, because the mean of its divisors is an integer number (1191645).

Almost surely, 2^21313888 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21313888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21449610).

21313888 is an abundant number, since it is smaller than the sum of its proper divisors (21585332).

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

21313888 is an equidigital number, since it uses as much as digits as its factorization.

21313888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 311 (or 242 counting only the distinct ones).

The product of its digits is 9216, while the sum is 34.

The square root of 21313888 is about 4616.6966545356. The cubic root of 21313888 is about 277.2602176174.

It can be divided in two parts, 21313 and 888, that added together give a square (22201 = 149²).

The spelling of 21313888 in words is "twenty-one million, three hundred thirteen thousand, eight hundred eighty-eight".