21539453 has 8 divisors (see below), whose sum is σ = 23515128. Its totient is φ = 19609344.

The previous prime is 21539449. The next prime is 21539467. The reversal of 21539453 is 35493512.

It can be written as a sum of positive squares in 4 ways, for example, as 407044 + 21132409 = 638^2 + 4597^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21539453 - 2² = 21539449 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21539653) 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 7 ways as a sum of consecutive naturals, for example, 10400 + ... + 12297.

It is an arithmetic number, because the mean of its divisors is an integer number (2939391).

Almost surely, 2^21539453 is an apocalyptic number.

It is an amenable number.

21539453 is a deficient number, since it is larger than the sum of its proper divisors (1975675).

21539453 is a wasteful number, since it uses less digits than its factorization.

21539453 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22783.

The product of its digits is 16200, while the sum is 32.

The square root of 21539453 is about 4641.0616242407. The cubic root of 21539453 is about 278.2348695741.

The spelling of 21539453 in words is "twenty-one million, five hundred thirty-nine thousand, four hundred fifty-three".