21197698 has 4 divisors (see below), whose sum is σ = 31796550. Its totient is φ = 10598848.

The previous prime is 21197681. The next prime is 21197699. The reversal of 21197698 is 89679112.

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., 18896409 + 2301289 = 4347^2 + 1517^2 .

It is not an unprimeable number, because it can be changed into a prime (21197699) 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, 5299423 + ... + 5299426.

Almost surely, 2^21197698 is an apocalyptic number.

21197698 is a deficient number, since it is larger than the sum of its proper divisors (10598852).

21197698 is a wasteful number, since it uses less digits than its factorization.

21197698 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10598851.

The product of its digits is 54432, while the sum is 43.

The square root of 21197698 is about 4604.0957852764. The cubic root of 21197698 is about 276.7554828477.

The spelling of 21197698 in words is "twenty-one million, one hundred ninety-seven thousand, six hundred ninety-eight".