21084197 has 4 divisors (see below), whose sum is σ = 21277740. Its totient is φ = 20890656.

The previous prime is 21084187. The next prime is 21084227. The reversal of 21084197 is 79148012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5764801 + 15319396 = 2401^2 + 3914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21084197 - 2⁸ = 21083941 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 (21084187) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96608 + ... + 96825.

It is an arithmetic number, because the mean of its divisors is an integer number (5319435).

Almost surely, 2^21084197 is an apocalyptic number.

It is an amenable number.

21084197 is a deficient number, since it is larger than the sum of its proper divisors (193543).

21084197 is a wasteful number, since it uses less digits than its factorization.

21084197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193542.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 21084197 is about 4591.7531510307. The cubic root of 21084197 is about 276.2606452222.

The spelling of 21084197 in words is "twenty-one million, eighty-four thousand, one hundred ninety-seven".