21033640 has 32 divisors (see below), whose sum is σ = 47472480. Its totient is φ = 8387392.

The previous prime is 21033631. The next prime is 21033647. The reversal of 21033640 is 4633012.

It is not an unprimeable number, because it can be changed into a prime (21033647) 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, 17127 + ... + 18313.

It is an arithmetic number, because the mean of its divisors is an integer number (1483515).

Almost surely, 2^21033640 is an apocalyptic number.

21033640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21033640 is an abundant number, since it is smaller than the sum of its proper divisors (26438840).

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

21033640 is a wasteful number, since it uses less digits than its factorization.

21033640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1641 (or 1637 counting only the distinct ones).

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

The square root of 21033640 is about 4586.2446511280. The cubic root of 21033640 is about 276.0396568375.

Adding to 21033640 its reverse (4633012), we get a palindrome (25666652).

The spelling of 21033640 in words is "twenty-one million, thirty-three thousand, six hundred forty".