21523122 has 48 divisors (see below), whose sum is σ = 50737752. Its totient is φ = 6566400.

The previous prime is 21523093. The next prime is 21523171. The reversal of 21523122 is 22132512.

21523122 is a `hidden beast` number, since 21 + 523 + 122 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 20061441 + 1461681 = 4479^2 + 1209^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21523095 and 21523104.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10372 + ... + 12272.

Almost surely, 2^21523122 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21523122, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25368876).

21523122 is an abundant number, since it is smaller than the sum of its proper divisors (29214630).

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

21523122 is a wasteful number, since it uses less digits than its factorization.

21523122 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1963 (or 1960 counting only the distinct ones).

The product of its digits is 240, while the sum is 18.

The square root of 21523122 is about 4639.3018871378. The cubic root of 21523122 is about 278.1645334873.

Adding to 21523122 its reverse (22132512), we get a palindrome (43655634).

The spelling of 21523122 in words is "twenty-one million, five hundred twenty-three thousand, one hundred twenty-two".