21249635 has 16 divisors (see below), whose sum is σ = 28015200. Its totient is φ = 15344640.

The previous prime is 21249623. The next prime is 21249637. The reversal of 21249635 is 53694212.

It is a happy number.

It is not a de Polignac number, because 21249635 - 2¹⁶ = 21184099 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21249637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6899 + ... + 9491.

It is an arithmetic number, because the mean of its divisors is an integer number (1750950).

Almost surely, 2^21249635 is an apocalyptic number.

21249635 is a deficient number, since it is larger than the sum of its proper divisors (6765565).

21249635 is a wasteful number, since it uses less digits than its factorization.

21249635 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2758.

The product of its digits is 12960, while the sum is 32.

The square root of 21249635 is about 4609.7326386679. The cubic root of 21249635 is about 276.9813269657.

The spelling of 21249635 in words is "twenty-one million, two hundred forty-nine thousand, six hundred thirty-five".