21649535 has 4 divisors (see below), whose sum is σ = 25979448. Its totient is φ = 17319624.

The previous prime is 21649499. The next prime is 21649541. The reversal of 21649535 is 53594612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21649535 - 2¹² = 21645439 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21649495 and 21649504.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2164949 + ... + 2164958.

It is an arithmetic number, because the mean of its divisors is an integer number (6494862).

Almost surely, 2^21649535 is an apocalyptic number.

21649535 is a deficient number, since it is larger than the sum of its proper divisors (4329913).

21649535 is an equidigital number, since it uses as much as digits as its factorization.

21649535 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4329912.

The product of its digits is 32400, while the sum is 35.

The square root of 21649535 is about 4652.9060811497. The cubic root of 21649535 is about 278.7080573946.

The spelling of 21649535 in words is "twenty-one million, six hundred forty-nine thousand, five hundred thirty-five".