21197853 has 6 divisors (see below), whose sum is σ = 30619134. Its totient is φ = 14131896.

The previous prime is 21197851. The next prime is 21197857. The reversal of 21197853 is 35879112.

It can be written as a sum of positive squares in only one way, i.e., 12089529 + 9108324 = 3477^2 + 3018^2 .

It is not a de Polignac number, because 21197853 - 2¹ = 21197851 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21197851) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1177650 + ... + 1177667.

It is an arithmetic number, because the mean of its divisors is an integer number (5103189).

Almost surely, 2^21197853 is an apocalyptic number.

It is an amenable number.

21197853 is a deficient number, since it is larger than the sum of its proper divisors (9421281).

21197853 is a wasteful number, since it uses less digits than its factorization.

21197853 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2355323 (or 2355320 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 21197853 is about 4604.1126180840. The cubic root of 21197853 is about 276.7561574020.

The spelling of 21197853 in words is "twenty-one million, one hundred ninety-seven thousand, eight hundred fifty-three".