21263040 has 224 divisors, whose sum is σ = 79004160. Its totient is φ = 5372928.

The previous prime is 21262999. The next prime is 21263041. The reversal of 21263040 is 4036212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21263041) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 198667 + ... + 198773.

Almost surely, 2^21263040 is an apocalyptic number.

21263040 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 21263040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39502080).

21263040 is an abundant number, since it is smaller than the sum of its proper divisors (57741120).

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

21263040 is a wasteful number, since it uses less digits than its factorization.

21263040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21263040 is about 4611.1863983144. The cubic root of 21263040 is about 277.0395578359.

Adding to 21263040 its reverse (4036212), we get a palindrome (25299252).

The spelling of 21263040 in words is "twenty-one million, two hundred sixty-three thousand, forty".