21397249 has 8 divisors (see below), whose sum is σ = 22833440. Its totient is φ = 19992096.

The previous prime is 21397217. The next prime is 21397253. The reversal of 21397249 is 94279312.

21397249 = 308² + 309² + ... + 453².

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 21397249 - 2⁵ = 21397217 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21397279) 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, 6327 + ... + 9100.

It is an arithmetic number, because the mean of its divisors is an integer number (2854180).

Almost surely, 2^21397249 is an apocalyptic number.

It is an amenable number.

21397249 is a deficient number, since it is larger than the sum of its proper divisors (1436191).

21397249 is a wasteful number, since it uses less digits than its factorization.

21397249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15519.

The product of its digits is 27216, while the sum is 37.

The square root of 21397249 is about 4625.7160526777. The cubic root of 21397249 is about 277.6212126362.

The spelling of 21397249 in words is "twenty-one million, three hundred ninety-seven thousand, two hundred forty-nine".