21397373 has 8 divisors (see below), whose sum is σ = 22803192. Its totient is φ = 20007936.

The previous prime is 21397349. The next prime is 21397379. The reversal of 21397373 is 37379312.

It can be written as a sum of positive squares in 4 ways, for example, as 4439449 + 16957924 = 2107^2 + 4118^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21397373 is a prime.

It is a super-2 number, since 2×21397373² = 915695142602258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21397379) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1340 + ... + 6677.

It is an arithmetic number, because the mean of its divisors is an integer number (2850399).

Almost surely, 2^21397373 is an apocalyptic number.

It is an amenable number.

21397373 is a deficient number, since it is larger than the sum of its proper divisors (1405819).

21397373 is a wasteful number, since it uses less digits than its factorization.

21397373 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8191.

The product of its digits is 23814, while the sum is 35.

The square root of 21397373 is about 4625.7294559885. The cubic root of 21397373 is about 277.6217489196.

The spelling of 21397373 in words is "twenty-one million, three hundred ninety-seven thousand, three hundred seventy-three".