21497338 has 4 divisors (see below), whose sum is σ = 32246010. Its totient is φ = 10748668.

The previous prime is 21497321. The next prime is 21497339. The reversal of 21497338 is 83379412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 21409129 + 88209 = 4627^2 + 297^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21497297 and 21497306.

It is not an unprimeable number, because it can be changed into a prime (21497339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5374333 + ... + 5374336.

Almost surely, 2^21497338 is an apocalyptic number.

21497338 is a deficient number, since it is larger than the sum of its proper divisors (10748672).

21497338 is a wasteful number, since it uses less digits than its factorization.

21497338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10748671.

The product of its digits is 36288, while the sum is 37.

The square root of 21497338 is about 4636.5221880198. The cubic root of 21497338 is about 278.0534117480.

The spelling of 21497338 in words is "twenty-one million, four hundred ninety-seven thousand, three hundred thirty-eight".