21317376 has 72 divisors (see below), whose sum is σ = 58204944. Its totient is φ = 6922240.

The previous prime is 21317357. The next prime is 21317377. The reversal of 21317376 is 67371312.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21317377) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31150 + ... + 31826.

It is an arithmetic number, because the mean of its divisors is an integer number (808402).

Almost surely, 2^21317376 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 21317376, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29102472).

21317376 is an abundant number, since it is smaller than the sum of its proper divisors (36887568).

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

21317376 is an equidigital number, since it uses as much as digits as its factorization.

21317376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 737 (or 723 counting only the distinct ones).

The product of its digits is 5292, while the sum is 30.

The square root of 21317376 is about 4617.0743983609. The cubic root of 21317376 is about 277.2753412603.

Adding to 21317376 its reverse (67371312), we get a palindrome (88688688).

The spelling of 21317376 in words is "twenty-one million, three hundred seventeen thousand, three hundred seventy-six".