21263500 has 72 divisors (see below), whose sum is σ = 49611744. Its totient is φ = 7946400.

The previous prime is 21263497. The next prime is 21263503. The reversal of 21263500 is 536212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21263497) and next prime (21263503).

It is a hoax number, since the sum of its digits (19) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21263503) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 494479 + ... + 494521.

It is an arithmetic number, because the mean of its divisors is an integer number (689052).

Almost surely, 2^21263500 is an apocalyptic number.

21263500 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 21263500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24805872).

21263500 is an abundant number, since it is smaller than the sum of its proper divisors (28348244).

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

21263500 is a wasteful number, since it uses less digits than its factorization.

21263500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128 (or 73 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21263500 is about 4611.2362767484. The cubic root of 21263500 is about 277.0415556261.

Adding to 21263500 its reverse (536212), we get a palindrome (21799712).

The spelling of 21263500 in words is "twenty-one million, two hundred sixty-three thousand, five hundred".