21633040 has 160 divisors (see below), whose sum is σ = 61996032. Its totient is φ = 6912000.

The previous prime is 21633023. The next prime is 21633047. The reversal of 21633040 is 4033612.

It is a junction number, because it is equal to n+sod(n) for n = 21632999 and 21633017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21633047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 354610 + ... + 354670.

Almost surely, 2^21633040 is an apocalyptic number.

21633040 is a gapful number since it is divisible by the number (20) 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 21633040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30998016).

21633040 is an abundant number, since it is smaller than the sum of its proper divisors (40362992).

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

21633040 is a wasteful number, since it uses less digits than its factorization.

21633040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 19.

The square root of 21633040 is about 4651.1331952547. The cubic root of 21633040 is about 278.6372559128.

Adding to 21633040 its reverse (4033612), we get a palindrome (25666652).

The spelling of 21633040 in words is "twenty-one million, six hundred thirty-three thousand, forty".