21397441 has 8 divisors (see below), whose sum is σ = 24399144. Its totient is φ = 18589440.

The previous prime is 21397427. The next prime is 21397451. The reversal of 21397441 is 14479312.

It can be written as a sum of positive squares in 4 ways, for example, as 9000000 + 12397441 = 3000^2 + 3521^2 .

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 21397441 - 2¹¹ = 21395393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21397421) 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, 48190 + ... + 48631.

It is an arithmetic number, because the mean of its divisors is an integer number (3049893).

Almost surely, 2^21397441 is an apocalyptic number.

It is an amenable number.

21397441 is a deficient number, since it is larger than the sum of its proper divisors (3001703).

21397441 is a wasteful number, since it uses less digits than its factorization.

21397441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96851.

The product of its digits is 6048, while the sum is 31.

The square root of 21397441 is about 4625.7368061748. The cubic root of 21397441 is about 277.6220430096.

The spelling of 21397441 in words is "twenty-one million, three hundred ninety-seven thousand, four hundred forty-one".