21197541 has 4 divisors (see below), whose sum is σ = 28263392. Its totient is φ = 14131692.

The previous prime is 21197489. The next prime is 21197551. The reversal of 21197541 is 14579112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21197541 - 2¹⁴ = 21181157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21197499 and 21197508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21197551) 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 3 ways as a sum of consecutive naturals, for example, 3532921 + ... + 3532926.

It is an arithmetic number, because the mean of its divisors is an integer number (7065848).

Almost surely, 2^21197541 is an apocalyptic number.

It is an amenable number.

21197541 is a deficient number, since it is larger than the sum of its proper divisors (7065851).

21197541 is an equidigital number, since it uses as much as digits as its factorization.

21197541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7065850.

The product of its digits is 2520, while the sum is 30.

The square root of 21197541 is about 4604.0787352086. The cubic root of 21197541 is about 276.7547995861.

The spelling of 21197541 in words is "twenty-one million, one hundred ninety-seven thousand, five hundred forty-one".