21523384 has 16 divisors (see below), whose sum is σ = 40528800. Its totient is φ = 10715712.

The previous prime is 21523361. The next prime is 21523387. The reversal of 21523384 is 48332512.

It is a super-2 number, since 2×21523384² = 926512117622912, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523387) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3717 + ... + 7540.

It is an arithmetic number, because the mean of its divisors is an integer number (2533050).

Almost surely, 2^21523384 is an apocalyptic number.

It is an amenable number.

21523384 is a deficient number, since it is larger than the sum of its proper divisors (19005416).

21523384 is a wasteful number, since it uses less digits than its factorization.

21523384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11502 (or 11498 counting only the distinct ones).

The product of its digits is 5760, while the sum is 28.

The square root of 21523384 is about 4639.3301240589. The cubic root of 21523384 is about 278.1656621776.

Adding to 21523384 its reverse (48332512), we get a palindrome (69855896).

The spelling of 21523384 in words is "twenty-one million, five hundred twenty-three thousand, three hundred eighty-four".