21249835 has 4 divisors (see below), whose sum is σ = 25499808. Its totient is φ = 16999864.

The previous prime is 21249829. The next prime is 21249841. The reversal of 21249835 is 53894212.

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

It is an interprime number because it is at equal distance from previous prime (21249829) and next prime (21249841).

It is a cyclic number.

It is not a de Polignac number, because 21249835 - 2⁷ = 21249707 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21249835.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2124979 + ... + 2124988.

It is an arithmetic number, because the mean of its divisors is an integer number (6374952).

Almost surely, 2^21249835 is an apocalyptic number.

21249835 is a deficient number, since it is larger than the sum of its proper divisors (4249973).

21249835 is an equidigital number, since it uses as much as digits as its factorization.

21249835 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4249972.

The product of its digits is 17280, while the sum is 34.

The square root of 21249835 is about 4609.7543318489. The cubic root of 21249835 is about 276.9821959389.

The spelling of 21249835 in words is "twenty-one million, two hundred forty-nine thousand, eight hundred thirty-five".