21240032 has 48 divisors (see below), whose sum is σ = 46230912. Its totient is φ = 9525120.

The previous prime is 21240001. The next prime is 21240049. The reversal of 21240032 is 23004212.

It is a super-2 number, since 2×21240032² = 902277918722048, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21239989 and 21240016.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28853 + ... + 29579.

It is an arithmetic number, because the mean of its divisors is an integer number (963144).

Almost surely, 2^21240032 is an apocalyptic number.

21240032 is a gapful number since it is divisible by the number (22) 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 21240032, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23115456).

21240032 is an abundant number, since it is smaller than the sum of its proper divisors (24990880).

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

21240032 is a wasteful number, since it uses less digits than its factorization.

21240032 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 831 (or 823 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 21240032 is about 4608.6909204242. The cubic root of 21240032 is about 276.9395967986.

Adding to 21240032 its reverse (23004212), we get a palindrome (44244244).

The spelling of 21240032 in words is "twenty-one million, two hundred forty thousand, thirty-two".