21002240 has 96 divisors (see below), whose sum is σ = 57788640. Its totient is φ = 7176192.

The previous prime is 21002231. The next prime is 21002251. The reversal of 21002240 is 4220012.

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, 71534 + ... + 71826.

It is an arithmetic number, because the mean of its divisors is an integer number (601965).

Almost surely, 2^21002240 is an apocalyptic number.

21002240 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 21002240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28894320).

21002240 is an abundant number, since it is smaller than the sum of its proper divisors (36786400).

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

21002240 is an equidigital number, since it uses as much as digits as its factorization.

21002240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327 (or 307 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21002240 is about 4582.8200924758. The cubic root of 21002240 is about 275.9022267975.

Adding to 21002240 its reverse (4220012), we get a palindrome (25222252).

The spelling of 21002240 in words is "twenty-one million, two thousand, two hundred forty".