21152523 has 16 divisors (see below), whose sum is σ = 32368896. Its totient is φ = 12036000.

The previous prime is 21152519. The next prime is 21152561. The reversal of 21152523 is 32525112.

It is not a de Polignac number, because 21152523 - 2² = 21152519 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 21152523.

It is not an unprimeable number, because it can be changed into a prime (21152423) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3265 + ... + 7277.

It is an arithmetic number, because the mean of its divisors is an integer number (2023056).

Almost surely, 2^21152523 is an apocalyptic number.

21152523 is a deficient number, since it is larger than the sum of its proper divisors (11216373).

21152523 is a wasteful number, since it uses less digits than its factorization.

21152523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4274.

The product of its digits is 600, while the sum is 21.

The square root of 21152523 is about 4599.1872108015. The cubic root of 21152523 is about 276.5587426027.

Adding to 21152523 its reverse (32525112), we get a palindrome (53677635).

The spelling of 21152523 in words is "twenty-one million, one hundred fifty-two thousand, five hundred twenty-three".