21497738 has 4 divisors (see below), whose sum is σ = 32246610. Its totient is φ = 10748868.

The previous prime is 21497731. The next prime is 21497761. The reversal of 21497738 is 83779412.

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., 19298449 + 2199289 = 4393^2 + 1483^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21497695 and 21497704.

It is not an unprimeable number, because it can be changed into a prime (21497731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5374433 + ... + 5374436.

Almost surely, 2^21497738 is an apocalyptic number.

21497738 is a deficient number, since it is larger than the sum of its proper divisors (10748872).

21497738 is a wasteful number, since it uses less digits than its factorization.

21497738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10748871.

The product of its digits is 84672, while the sum is 41.

The square root of 21497738 is about 4636.5653235989. The cubic root of 21497738 is about 278.0551363131.

The spelling of 21497738 in words is "twenty-one million, four hundred ninety-seven thousand, seven hundred thirty-eight".