21532123 has 6 divisors (see below), whose sum is σ = 22301084. Its totient is φ = 20788824.

The previous prime is 21532097. The next prime is 21532169. The reversal of 21532123 is 32123512.

It is not a de Polignac number, because 21532123 - 2²¹ = 19434971 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21532123.

It is not an unprimeable number, because it can be changed into a prime (21532223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11961 + ... + 13642.

Almost surely, 2^21532123 is an apocalyptic number.

21532123 is a deficient number, since it is larger than the sum of its proper divisors (768961).

21532123 is an equidigital number, since it uses as much as digits as its factorization.

21532123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25661 (or 25632 counting only the distinct ones).

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

The square root of 21532123 is about 4640.2718670354. The cubic root of 21532123 is about 278.2033043500.

Adding to 21532123 its reverse (32123512), we get a palindrome (53655635).

It can be divided in two parts, 2 and 1532123, that added together give a triangular number (1532125 = T₁₇₅₀).

The spelling of 21532123 in words is "twenty-one million, five hundred thirty-two thousand, one hundred twenty-three".