21455197 has 8 divisors (see below), whose sum is σ = 21785400. Its totient is φ = 21127680.

The previous prime is 21455183. The next prime is 21455257. The reversal of 21455197 is 79155412.

It can be written as a sum of positive squares in 4 ways, for example, as 27556 + 21427641 = 166^2 + 4629^2 .

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 21455197 - 2¹⁹ = 20930909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21455107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19929 + ... + 20977.

It is an arithmetic number, because the mean of its divisors is an integer number (2723175).

Almost surely, 2^21455197 is an apocalyptic number.

It is an amenable number.

21455197 is a deficient number, since it is larger than the sum of its proper divisors (330203).

21455197 is a wasteful number, since it uses less digits than its factorization.

21455197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1343.

The product of its digits is 12600, while the sum is 34.

The square root of 21455197 is about 4631.9754964810. The cubic root of 21455197 is about 277.8716045292.

The spelling of 21455197 in words is "twenty-one million, four hundred fifty-five thousand, one hundred ninety-seven".