21245291 has 8 divisors (see below), whose sum is σ = 22543920. Its totient is φ = 19952128.

The previous prime is 21245281. The next prime is 21245293. The reversal of 21245291 is 19254212.

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 21245291 - 2⁶ = 21245227 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 21245291.

It is not an unprimeable number, because it can be changed into a prime (21245293) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8915 + ... + 11043.

It is an arithmetic number, because the mean of its divisors is an integer number (2817990).

Almost surely, 2^21245291 is an apocalyptic number.

21245291 is a deficient number, since it is larger than the sum of its proper divisors (1298629).

21245291 is a wasteful number, since it uses less digits than its factorization.

21245291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2733.

The product of its digits is 1440, while the sum is 26.

The square root of 21245291 is about 4609.2614375841. The cubic root of 21245291 is about 276.9624515217.

The spelling of 21245291 in words is "twenty-one million, two hundred forty-five thousand, two hundred ninety-one".