21230040 has 128 divisors (see below), whose sum is σ = 70963200. Its totient is φ = 5045760.

The previous prime is 21230023. The next prime is 21230047. The reversal of 21230040 is 4003212.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21229998 and 21230025.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21230047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48141 + ... + 48579.

It is an arithmetic number, because the mean of its divisors is an integer number (554400).

Almost surely, 2^21230040 is an apocalyptic number.

21230040 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 21230040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35481600).

21230040 is an abundant number, since it is smaller than the sum of its proper divisors (49733160).

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

21230040 is a wasteful number, since it uses less digits than its factorization.

21230040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497 (or 493 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21230040 is about 4607.6067540536. The cubic root of 21230040 is about 276.8961628639.

Adding to 21230040 its reverse (4003212), we get a palindrome (25233252).

The spelling of 21230040 in words is "twenty-one million, two hundred thirty thousand, forty".