21481539 has 8 divisors (see below), whose sum is σ = 28674240. Its totient is φ = 14304936.

The previous prime is 21481531. The next prime is 21481549. The reversal of 21481539 is 93518412.

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

It is not a de Polignac number, because 21481539 - 2³ = 21481531 is a prime.

It is a super-2 number, since 2×21481539² = 922913035617042, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21481531) 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 7 ways as a sum of consecutive naturals, for example, 457 + ... + 6570.

It is an arithmetic number, because the mean of its divisors is an integer number (3584280).

Almost surely, 2^21481539 is an apocalyptic number.

21481539 is a deficient number, since it is larger than the sum of its proper divisors (7192701).

21481539 is a wasteful number, since it uses less digits than its factorization.

21481539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8049.

The product of its digits is 8640, while the sum is 33.

The square root of 21481539 is about 4634.8181194088. The cubic root of 21481539 is about 277.9852786228.

The spelling of 21481539 in words is "twenty-one million, four hundred eighty-one thousand, five hundred thirty-nine".