21131535 has 8 divisors (see below), whose sum is σ = 33810480. Its totient is φ = 11270144.

The previous prime is 21131531. The next prime is 21131567. The reversal of 21131535 is 53513112.

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 21131535 - 2² = 21131531 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131531) 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, 704370 + ... + 704399.

It is an arithmetic number, because the mean of its divisors is an integer number (4226310).

Almost surely, 2^21131535 is an apocalyptic number.

21131535 is a deficient number, since it is larger than the sum of its proper divisors (12678945).

21131535 is a wasteful number, since it uses less digits than its factorization.

21131535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408777.

The product of its digits is 450, while the sum is 21.

The square root of 21131535 is about 4596.9049370201. The cubic root of 21131535 is about 276.4672431048.

Adding to 21131535 its reverse (53513112), we get a palindrome (74644647).

The spelling of 21131535 in words is "twenty-one million, one hundred thirty-one thousand, five hundred thirty-five".