21863120 has 20 divisors (see below), whose sum is σ = 50831940. Its totient is φ = 8745216.

The previous prime is 21863119. The next prime is 21863141. The reversal of 21863120 is 2136812.

It can be written as a sum of positive squares in 2 ways, for example, as 9388096 + 12475024 = 3064^2 + 3532^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×21863120² = 955992032268800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 136565 + ... + 136724.

It is an arithmetic number, because the mean of its divisors is an integer number (2541597).

Almost surely, 2^21863120 is an apocalyptic number.

21863120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21863120 is an abundant number, since it is smaller than the sum of its proper divisors (28968820).

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

21863120 is a wasteful number, since it uses less digits than its factorization.

21863120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273302 (or 273296 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21863120 is about 4675.8015355659. The cubic root of 21863120 is about 279.6215976871.

Adding to 21863120 its reverse (2136812), we get a palindrome (23999932).

The spelling of 21863120 in words is "twenty-one million, eight hundred sixty-three thousand, one hundred twenty".