21523145 has 32 divisors (see below), whose sum is σ = 30965760. Its totient is φ = 14051520.

The previous prime is 21523093. The next prime is 21523171. The reversal of 21523145 is 54132512.

It is not a de Polignac number, because 21523145 - 2⁸ = 21522889 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21523145.

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 31 ways as a sum of consecutive naturals, for example, 89936 + ... + 90174.

It is an arithmetic number, because the mean of its divisors is an integer number (967680).

Almost surely, 2^21523145 is an apocalyptic number.

It is an amenable number.

21523145 is a deficient number, since it is larger than the sum of its proper divisors (9442615).

21523145 is a wasteful number, since it uses less digits than its factorization.

21523145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 365.

The product of its digits is 1200, while the sum is 23.

The square root of 21523145 is about 4639.3043659583. The cubic root of 21523145 is about 278.1646325712.

Adding to 21523145 its reverse (54132512), we get a palindrome (75655657).

The spelling of 21523145 in words is "twenty-one million, five hundred twenty-three thousand, one hundred forty-five".