21163506 has 64 divisors (see below), whose sum is σ = 52835328. Its totient is φ = 5502528.

The previous prime is 21163481. The next prime is 21163507. The reversal of 21163506 is 60536112.

It is not an unprimeable number, because it can be changed into a prime (21163507) 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, 45085 + ... + 45551.

It is an arithmetic number, because the mean of its divisors is an integer number (825552).

Almost surely, 2^21163506 is an apocalyptic number.

21163506 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21163506, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26417664).

21163506 is an abundant number, since it is smaller than the sum of its proper divisors (31671822).

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

21163506 is a wasteful number, since it uses less digits than its factorization.

21163506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 575.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21163506 is about 4600.3810711723. The cubic root of 21163506 is about 276.6066000791.

Adding to 21163506 its reverse (60536112), we get a palindrome (81699618).

The spelling of 21163506 in words is "twenty-one million, one hundred sixty-three thousand, five hundred six".