21397245 has 32 divisors (see below), whose sum is σ = 36115200. Its totient is φ = 10796544.

The previous prime is 21397217. The next prime is 21397253. The reversal of 21397245 is 54279312.

It is not a de Polignac number, because 21397245 - 2⁹ = 21396733 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 37321 + ... + 37889.

It is an arithmetic number, because the mean of its divisors is an integer number (1128600).

Almost surely, 2^21397245 is an apocalyptic number.

It is an amenable number.

21397245 is a deficient number, since it is larger than the sum of its proper divisors (14717955).

21397245 is a wasteful number, since it uses less digits than its factorization.

21397245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 709.

The product of its digits is 15120, while the sum is 33.

The square root of 21397245 is about 4625.7156203122. The cubic root of 21397245 is about 277.6211953368.

The spelling of 21397245 in words is "twenty-one million, three hundred ninety-seven thousand, two hundred forty-five".