21243376 has 80 divisors (see below), whose sum is σ = 52639488. Its totient is φ = 8064000.

The previous prime is 21243361. The next prime is 21243403. The reversal of 21243376 is 67334212.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52776 + ... + 53176.

Almost surely, 2^21243376 is an apocalyptic number.

21243376 is the 2464-th nonagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21243376, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26319744).

21243376 is an abundant number, since it is smaller than the sum of its proper divisors (31396112).

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

21243376 is a wasteful number, since it uses less digits than its factorization.

21243376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470 (or 464 counting only the distinct ones).

The product of its digits is 6048, while the sum is 28.

The square root of 21243376 is about 4609.0536989712. The cubic root of 21243376 is about 276.9541296928.

Adding to 21243376 its reverse (67334212), we get a palindrome (88577588).

The spelling of 21243376 in words is "twenty-one million, two hundred forty-three thousand, three hundred seventy-six".