21537453 has 64 divisors (see below), whose sum is σ = 37711872. Its totient is φ = 10644480.

The previous prime is 21537427. The next prime is 21537473. The reversal of 21537453 is 35473512.

It is not a de Polignac number, because 21537453 - 2⁶ = 21537389 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 21537453.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21537473) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 353043 + ... + 353103.

It is an arithmetic number, because the mean of its divisors is an integer number (589248).

Almost surely, 2^21537453 is an apocalyptic number.

21537453 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21537453 is a deficient number, since it is larger than the sum of its proper divisors (16174419).

21537453 is a wasteful number, since it uses less digits than its factorization.

21537453 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154.

The product of its digits is 12600, while the sum is 30.

The square root of 21537453 is about 4640.8461512961. The cubic root of 21537453 is about 278.2262576723.

The spelling of 21537453 in words is "twenty-one million, five hundred thirty-seven thousand, four hundred fifty-three".